Slave- Based Activities

Annex: Calculating the weight of slave-based activities in the GDP of Holland and the Dutch Republic – underlying methods, data and assumptions

Pepijn Brandon and Ulbe Bosma

The aim of this annex is to provide a detailed overview of the model and estimates for each individual branch included in our total underlying our calculation of the weight of slave- based activities in the GDP of the province of Holland, as well as the Dutch Republic as a whole. The annex will not restate the arguments for following the model of Van Zanden and Van Leeuwen, which have been presented in the article itself, or a detailed investigation of their model, for which we refer the reader to the original article in which they presented their findings.1

1.  International trade and shipping

In the model of Van Zanden and Van Leeuwen, international trade and shipping contributed fl.42.6 million and fl.8.5 million respectively to Holland’s GDP in 1770, or 24.1 and 4.8 per cent. The overall size of all imports and exports of the Dutch Republic in the 1770s amounted to around fl.250 million, of which around eighty per cent or fl.200 million would have accrued to the province of Holland., The combined value added in international shipping and trade according to the model of Van Zanden and Van Leeuwen would thus contribute to GDP at approximately one quarter of the total value of all commodities coming into and going out of the Dutch Republic, measured in Dutch prices. Given the importance of Atlantic commerce in the total trade of Holland in the second half of the eighteenth century, it can be expected that the main contribution of slave-based activities to the GDP will be found under these two posts.2

1 J.L. van Zanden and B. van Leeuwen, ‘Persistent but not consistent. The growth of national income in Holland 1347-1807’, Explorations in Economic History 49 (2012) 119-130, and online annexes.

2 Patick O’Brien estimated that British inter-continental trade contributed 15 per cent of the total value of the trade in profits alone for merchant houses, shipping companies and insurers (the latter are subsumed under

Van Zanden and Van Leeuwen estimated the total value of trade with different regions of Europe, Asia and the Atlantic, and have derived benchmarks for value added in shipping and trade with each of these regions on the basis of generalized assumptions on the value of inputs before the commodities traded came into the hands of the merchants and the costs of shipping, wages and profits, and Holland’s share in total Dutch trade. While we would prefer to employ the reverse method of estimation, starting from the value added in shipping and trade for specific goods such as coffee and sugar, we will here of necessity start from our findings for the total value of slave-based commodity trade on different routes to calculate value added in shipping and trade following the procedure that Van Zanden and Van Leeuwen developed.

The first difficulty is to determine the total value (in current prices) of the trade on the different trading routes that was slave-based. All extant figures for the value of eighteenth- century trade are rough approximations on the basis of unreliable records for customs and excises, complemented with contemporary observations.3 This is true for the trade in all commodities, not only those that were slave-based. Our starting point thus must be to carefully compare slave-based trade streams with the existing estimates for the total trade of the Dutch Republic.

The slave-based trade activities can be divided in two parts.

  1. Direct imports of slave-produced goods from the Atlantic world, both Dutch and non- Dutch, and direct exports from Holland to the Atlantic world for the maintenance of slave plantations in Dutch and non-Dutch slave-colonies;
  2. Imports and re-exports of slave-produced goods within Europe, and imports of European goods for re-export for the maintenance of slave plantations in Dutch and non-Dutch slave-colonies;

Both parts contain a component of imports, exports and re-exports for the slave trade, which in some trade-estimates are at least partially treated as a separate stream, and in some are

commercial profits in the model of Van Zanden and Van Leeuwen). Guillaume Daudin made a similar estimation for France and England on the basis of slightly different assumptions, and came at 17.6 per cent for France and 17.3 per cent for Britain. All three figures cited in G. Daudin, ‘Profits du commerce intercontinental et croissance dans la France du XVIIIe siècle’, Revue économique 57:3 (2006) 605-613, 606. The GDP of course does not only measure profits, but also other forms of income (wages and rent).

3 These problems are discussed at length in J. de Vries and A. van der Woude, The first modern economy. Success, failure, and perseverance of the Dutch economy, 1500-1815 (Cambridge 1997). FULL BIBLIOGRAPHICAL REFERENCES NEEDED THROUGHOUT

subsumed under a general heading such as ‘Atlantic trade’. Given the importance of this particular branch for debates on the economic contribution of slavery to the Dutch economy so far, we will present activities related to the slave trade within a and b under separate headings marked α and β. The total size of a and b (which thus includes α and β of the slave trade) can then be used to calculate value added in shipping and trade per trade route using the same methods employed by Van Zanden and Van Leeuwen.

It must be noted that when calculating value added on the basis of the total size of trade flows, there is always a danger of counting inputs on the first leg of a voyage (e.g. importing guns for the slave trade into Middelburg) as part of the outputs of the second leg (the value of Dutch exports to the West-African coast). Another perennial problem in such calculations on the basis of trade flows is that the total value of goods traded is based on observations on the value of these goods when they entered the Dutch Republic, not on the prices at the point of acquisition or sale.4 The robustness of the model of Van Zanden and Van Leeuwen thus in large part relies on the way in which they reconstruct net trade flows, that do not count the value of imports as part of the value of re-exports, and are calculated on the basis of local prices at every point.5 The difference between the two is a potential source of considerable confusion, since our most solid overall data remain those for gross trade flows, while the size of net trade flows can only be based on inferences from small amounts of observations. Luckily, the records of the Middelburgse Commercie Compagnie (MCC) allow us to test whether the conclusions of Van Zanden and Van Leeuwen hold for the most important segment of our calculations: the Atlantic trade. Before going into this, however, it is necessary to provide an overview of the (gross) size of slave-based trade, on the basis of the extant estimates for the size of the Dutch Republic’s international trade in the final decades of the eighteenth century.

Dutch Atlantic trade

Direct imports: Various estimates are available for the size of Atlantic imports and exports around the period investigated by us. All of those are ultimately derived from combining

4 For the difficulty that variations in regional, national and international prices present to economic historians, see: M. Morineau, Pour une histoire économique vraie (Lille 1985).

5 It must also be noted that Van Zanden and Van Leeuwen do not include so-called ‘voorbijlandvaart’, trade by Dutch merchants that never entered Dutch ports, as do all other available estimates for Dutch trade in this period.

incomplete trade records derived from tax records (customs and excises and paalgeld) with the famous 1785 memorandum of VOC director Cornelis van der Oudermeulen, who gave aggregate figures for an unspecified year ‘around 1780’ (in all likelihood a composite of observations from the period immediately before and after the Fourth Anglo-Dutch War) of the value of trade on all important trading routes.6 Various authors have used different methods to adjust these figures, leading to not always entirely compatible results. These are summarized in Table 1 below.

6 C. van der Oudermeulen, ‘Iets dat tot voordeel der deelgenooten van de Oost-Indische Compagnie en tot nut van ieder ingezeten van dit gemeenebest kan strekken’, in: G.K. van Hogendorp, Stukken raakende den tegenwoordigen toestand der Bataafsche beziṄngen in Oost-Indië (The Hague/ Delft 1801).

Table 1 Different estimates for the total size of Dutch trade, ca. 1770

 c.1780 Neth.1770s Neth.c.1780 Neth.
RegionValue (f mln)%Value (f mln)%Value (f mln)%
Europe: Sont      
Import27 22   
Export17 17   
Europe: Rest      
Import  73   
Export  55   
River trade      
Import  10   
Export  20   
East Indies      
Import20.5 20   
Export14.5 2   
Import22 22.4   
Export7.5 6   

a De Vries made an upward readjustment of the earlier estimates for Atlantic trade made by him and Van der Woude, which is included here.

b Includes the Sont trade.

c Marked as ‘not specified’.

d The reason why Victor Enthoven’s figures for colonial trade are such outliers, is that he counts European imports and re-exports of colonial goods as part of the totals of Asiatic and Atlantic trade.

Sources: C. van der Oudermeulen, ‘Iets dat tot voordeel der deelgenooten van de Oost-Indische Compagnie en tot nut van ieder ingezeten van dit gemeenebest kan strekken’, in: G.K. van Hogendorp, Stukken raakende den tegenwoordigen toestand der Bataafsche bezittingen in Oost-Indië (The Hague/ Delft 1801) (excluding his figures for gold and coin exported to settle trade imbalances; J. de Vries and A. van der Woude, The first modern economy. Success, failure, and perseverance of the Dutch economy, 1500-1815 (Cambridge 1997) 499;

J. de Vries, ‘The Dutch Atlantic Economies’, in: P.A. Coclanis, The Atlantic economy during the seventeenth and eighteenth centuries. Organization, operation, practice, and personnel (Columbia 2005) 1-29, 28n63; V. Enthoven, ‘An assessment of Dutch Transatlantic commerce, 1585-1817’, in Johannes Postma and Victor Enthoven, Riches from Atlantic commerce. Dutch transatlantic trade and shipping, 1585-1817 (Leiden/ Boston

2003) 385-445, 444.

Table 2 presents various estimates for the size of direct Atlantic imports around 1770 and 1780.

Table 2 Direct imports from the Atlantic world around 1770 and around 1780 in fl. mln., different estimates

 vdOudermeulen c. 1780Van Stipriaan/ Klooster c. 1770 (partial estimates)De Vries, adjusted estimates c. 1770Our estimate 1770
Essequibo and Demerara4.5 1.7
St. Eustatius5.
West Indies (non- Dutch direct)0.75  0.75
West Africa   0.3
North America2.25  0.6

Sources: Van der Oudermeulen, ‘Iets dat tot voordeel’; A. van Stipriaan, Surinaams contrast. Roofbouw en overleven in een Caraïbische plantagekolonie 1750-1863 (Leiden 1993) 437; W. Klooster, Illicit riches. Dutch trade in the Caribbean, 1648-1795 (Leiden 1998) 176.

We come to our estimates for the various branches of Atlantic trade in the following way:

  • Suriname: Van Stipriaan’s figures for the value of Suriname export goods on the Amsterdam market are usually used as the basis for the overall development of Dutch imports from this region. However, these figures only include the value of sugar, coffee and cotton. While certainly by far the most important trade goods, there were some smaller trade goods that need to be taken into account. Most significantly, Van Stipriaan enlists yearly totals of 100,000 to almost 400,000 kilograms of cacao produced on Surinamese plantations in the 1770s. Including this and other minor trade

goods, we find it justified to add another fl.400,000 to Van Stipriaan’s Suriname import figure, bringing the total to fl.8.3 million.

  • Essequibo, Demerara and Berbice: De Vries and Van der Woude estimate that output from this region rose from 10 to 20 per cent of Surinamese output in 1700-1739 to over 50 per cent after 1780. According to Van der Oudermeulen’s estimation, the proportion in the latter year even was almost 70 per cent. Contemporary records and later estimates for the amounts of sugar and coffee imported from these Guyana Coast colonies, presented in the main text of the article in Table 4 and 5, suggest that coffee and sugar output only started to approximate the 50 per cent of Suriname output estimated by De Vries and Van der Woude in the second half of the 1770s, and stood much lower before that time. Preferring to err on the side of caution, we estimate the size of direct imports from Essequibo, Demerary and Berbice for our year at fl.1.7 million, 20 per cent of Suriname imports.
  • St. Eustatius and Curaçao: We have no reason to diverge from the yearly estimate of Klooster of fl.4.2 million and fl.2.8 million respectively.
  • West Indies (non-Dutch direct): this includes direct trade from St. Domingue and the British and Danish West Indies. We assumed that this trade was relatively stable, maintaining Van der Oudermeulen’s estimate of fl.750,000.
  • West Africa: Van der Oudermeulen only gives the estimation that a total of fl.2 million was tied up in the slave trade and West African trade, without giving further specifications. . It must be assumed that the largest part of this consisted of goods exported for the slave trade plus profits made by Dutch merchants on the sale of slaves in the Americas (which Van der Oudermeulen might have overestimated, but we will get back to this later in this section). Direct exports from West-Africa to the Dutch Republic by the 1770s were not large. Henk den Heijer shows that the WIC earned fl.131,920 in the sale of African goods in the years 1768-1770, and fl.257,450 in 1771-1773.7 Generously accounting for the increased role of private trade, we set the total of direct imports from West Africa at fl.300,000, with ivory and slave- produced Brazilian gold the most valuable components of this trade.
  • North America: Van der Oudermeulen estimated imports in 1784 at fl.2.25 million, with 52 ships clearing in Amsterdam and 13 in Rotterdam.8 Based on the paalgeld

7 H. den Heijer, Goud, ivoor en slaven. Scheepvaart en handel van de Tweede Westindische Compagnie op Afrika, 1674-1740 (Zutphen 1997) 370.

8 Van der Oudermeulen, ‘Iets dat tot voordeel’, 211.

records, Welling estimates the value of North-American imports in Amsterdam amounted to fl.323,000 in 1771, and fl.1,191,025 in 1784.9 Given the increase in Dutch-North American trade as a result of the War of Independence, we find it likely that the North American trade indeed was considerably smaller in 1770, putting the total direct imports from the North-American colonies at this period at fl.600,000. It must be noted that for 1771, Welling shows that over 80 per cent of North-American imports came from Charleston (Virginia), making it likely that most North-American imports were slave-produced.

Of the fl.18.65 million in direct Dutch imports from the Atlantic world, only the imports from West Africa and North America may have contained meaningful proportions of goods that were not slave-produced. Even when assuming that half of the trade with West Africa and North America was not related to slavery or the slave trade (almost certainly a gross over- estimation), we can set the total value of slave-based direct imports from the Atlantic world at fl.18.2 million.

Direct exports: De Vries and Van der Woude estimate the total value of exports to the Atlantic world at fl.6 million. They themselves acknowledge that this is a very rough figure, based only on estimated exports ‘to the colonies’ (presumably the Dutch colonies on the Guyana coast) plus Van der Oudermeulen’s estimate of total exports of fl.3.5 million to to St. Eustatius and Curaçao.10 A much older estimate by De Hullu put the export to the Dutch Atlantic colonies around 1800 at fl.7.4 million.11 Excluding exports to North-America and non-Dutch Atlantic colonies, but including the slave trade, Van der Oudermeulen put the direct exports from the Netherlands to the Atlantic world at fl.7.5 million, an amount that seems more or less consistent with De Hullu’s figure. Considering the figures on which De Vries and Van der Woude based their conservative estimate, it seems fair to say that their export figure actually does not reflect Atlantic exports in total, but only those exports that directly supported the Dutch Atlantic colonies, and through St. Eustatius and Curaçao to the other slave colonies in the West-Indies. We therefore take fl.6 million as the total value of

9 G.M. Welling, The prize of neutrality. Trade relations between Amsterdam and North America 1771-1817. A study in computational history (Amsterdam 1998) 200.

10 De Vries and Van der Woude, First modern economy, 474.

11 Cited in Enthoven, ‘Assessment’, 442.

slave-related exports to the Atlantic world, except for the direct export for the slave-trade, which we will now treat separately.

α. Slave trade: As noted above under direct exports, De Vries and Van der Woude’s estimates for the Atlantic trade are lower than Van der Oudermeulen’s, primarily because they seem to not include the slave trade. Indeed, Van der Oudermeulen estimated the export to the Dutch Atlantic colonies at fl.6 million and the African slave trade at fl.1.5 million.12 How accurate was Van der Oudermeulen’s estimate? According to the most recent reconstruction of revenues from slave-sales by Dutch traders, the total value of the slaves imported to the Dutch Guyanas and Caribbean in 1780 amounted to fl.1,226,234, the composition of which was:

  • 1,329 slaves disembarked in the Dutch Caribbean, sold at an average price of fl.312;
  • 2,267 slaves disembarked in the Dutch Guyanas, sold at an average price of fl.358.13

Including the direct exports of trade goods from Africa to the Dutch Republic, which Van der Oudermeulen included under the same bracket as the slave trade, indeed gives a total only slightly above fl.1.5 million. However, the value of exports related to the slave trade of course should be measured not by looking at the prices at which the slaves were sold in Suriname, but on the basis of the prices that Dutch merchants paid for their human cargoes on the African coast. For 1780, this amounted to a sum of fl.580,608 (accounting for 4,032 embarked slaves and average slave prices of fl.144). In 1770, it amounted to the much larger sum of fl.917,595 (6,797 embarked slaves at an average price of fl.135). These exports for the African slave trade should be added to the fl.6 million of direct exports to the Americas under ‘direct Atlantic exports’, bringing the total of direct Atlantic exports to fl.6.9 million.

Indirect slave-based imports and (re-)exports

Indirect Atlantic imports: The Dutch not only imported slave-produced commodities from their own colonies, but also imported large quantities of coffee and sugar from rival Atlantic empires, especially the French. Part of this trade came in through legal and illegal channels via the West-Indies, in particular through Curaçao and St. Eustatius. In addition, the Dutch

12 It is possible that De Vries and Van der Woude assumed that Van der Oudermeulen included the importation of slaves in the Dutch colonies in his figure of 6 million, as part of the triangular trade. This, however, is not the case. Van der Oudermeulen, ‘Iets dat tot voordeel’, 333.

13 Figures courtesy of Matthias van Rossum and Karwan Fatah-Black.

imported a substantial amount of colonial goods from French ports. The two routes were in inverse proportion, so that in years in which much coffee and sugar from St. Domingue was imported through St. Eustatius, less was imported directly from Bordeaux, and vice versa. In 1773, Dutch ships represented 29 per cent of the total foreign tonnage in the trade from Bordeaux.14 On the basis of the French Trade Records Database TOFLIT, it can be estimated that the Dutch imported fl.5 million worth of sugar and fl.3 million worth of coffee through French ports.15 Comparing to the immense European imports from French slave-plantations, imports through other European countries in 1770 (a down year for this side of the trade) was relatively small and throughout this period remained extremely volatile. For 1770 the Portuguese, English and Danish trade in these plantation goods added only fl.0.3 million for sugar, and fl.0.1 million for coffee. Sugar and coffee formed the most valuable goods produced by slaves of other Atlantic Empires imported through European ports. Other goods included gold produced in Brazilian mines that was imported through Lisbon, indigo produced in the Caribbean imported through French, British and Danish ports, and tobacco that was partly produced by slaves in North America and was imported in large quantities from Britain. The value of these imports was far from negligible. Using British export data, Roessingh has estimated that between 1770 and 1774, the Dutch imported an annual average of 86 million pounds of Virginia and Maryland tobacco from England and Scotland, at a price of around fl.0.21 per pound, totalling over fl.18 million in just five years.16 Dutch custom records give much lower import figures for tobacco, perhaps indicating large scale smuggling of this commodity. According to Welling’s paalgeld database, Amsterdam imported well over fl.400,000 worth of tobacco from the British North-American colonies and Brazil in the 1770s.17 However, the most important port of entry for tobacco was Rotterdam, not Amsterdam. French trade records show that Dutch merchants imported almost fl.500,000 in

14 S. Marzagalli, ‘The French Atlantic and the Dutch, late seventeenth-late eighteenth century’, in: G. Oostindie and J.V. Roitman (eds.), Dutch Atlantic connections, 1680-1800. Linking empires, bridging borders (Leiden/ Boston 2014) 103-118, 113.

15 French trade records database, TOFLIT 18, (accessed 31-05- 2019). Further estimates on the basis of these data courtesy of Tamira Combrink.

16 H.K.Roessingh, Inlandse tabak. Expansie en contractie van een handelsgewas in de 17e en 18e eeuw in Nederland (Zutphen 1976) 339. For the 1770s, it is not controversial to assume that the tobacco imported from the British colonies in North-America was produced by slaves. After 1700, slave labour rapidly replaced indentured servants up to the level of the supervisory and skilled jobs on the tobacco plantations of the Chesapeake. See: R.M. Menard, Migrants, servants and slaves. Unfree labor in colonial British America (Aldershot 2001) IV, 51. Tobacco and slavery were inexorably linked in Virginia already in the early eighteenth century the slave populations were concentrated in the tobacco belts. See: idem, III, 383-384. Maryland may have followed a little bit later. A.L. Kulikoff, Tobacco and slaves. Population, economy and society in

eighteenth-century prince George’s county, Maryland, dissertation Brandeis University 1976, 169, 171.

17 Welling, Prize of neutrality.

indigo in 1770.18 To be on the safe side, we estimate that taken together, these ‘lesser slave- based trade goods’ valued fl.2 million. As the British export figures for tobacco mentioned above make clear, this must be a considerable underestimation.

In addition, part of the fl.6 million worth of goods exported by the Dutch Republic to its Atlantic colonies for the upkeep of plantations (excluding goods for the slave trade, that will be treated separately below under β)were in turn imported from other European countries. De Vries and Van der Woude estimate that half of these exports were re-exports of goods procured in other parts of Europe. However, basing ourselves on estimates for the proportion of imported goods in the cargoes of Middelburg slave traders (see under subsection 3), we think it is more likely that the part of goods produced domestically formed only about one quarter of the total. Of course, the three quarters of the re-exported goods were not bought at the same prices at which they were re-exported. Allowing for a very generous discounting of 33 per cent, we estimate a value of fl.3 million in goods for export to the Atlantic colonies was imported from elsewhere in Europe.

Re-export of Atlantic slave-produced goods: Most slave-based imports into the Dutch Republic were not intended for domestic consumption, but were re-exported to Northern and Central Europe. Tamira Combrink estimates the total value of sugar exports from the Dutch Republic at fl.10.1 million for the year 1770. Practically all of this (98 per cent) was sugar from Atlantic slave plantations that was either re-exported as raw sugar or refined in the Dutch Republic first. Clearly, with these proportions and no alternative source of sugar at hand, dependency on Atlantic plantation production was almost complete, leading us to count fl.9.9 million as slave-based.19 The total value of coffee exports was fl.9.3 million. As in sugar, by far the largest proportion came from the Atlantic colonies, leaving a total of fl.7.5 million in slave-based coffee exports.20 Once again, the re-export of slave-based commodities of lesser importance in the overall trade needs to be taken into account, especially tobacco and indigo. Unfortunately, figures to base this estimate on at this time are not available, but

18 French trade records database, TOFLIT 18, (accessed 31-05- 2019).

19 The estimate is based on custom records for 1753 and 1790, and then interpolated on the basis of the trade volumes, with a correction factor based on the development of the Rhine trade. The corresponding values are estimated on the basis of Posthumus prices in Amsterdam. These prices are specific to kind and quality, making it necessary to estimate the mixture of types of sugar exported, which has been done by Tamira Combrink on the basis of qualitative and quantitative sources available and calculations of weight loss in sugar refining for the different types, the estimates of which will be presented in more detail in her dissertation.

20 Most imported coffee that was not produced by slaves in the Atlantic region was produced on Java, and might actually have involved significant proportions of slave labour. However, we do not examine revenues from forced labour in the East Indies as part of our total in this article.

estimating the total value of this trade at fl.1 million will put us once again on the conservative side. On this basis, we set the total value of slave-based European re-exports at fl.18.4 million.

β. Indirect imports and exports for the slave trade: Apart from European imports of slave- produced commodities, re-exports from the Netherlands of slave-produced commodities, and European imports aimed for re-export to the Dutch Atlantic colonies, the Dutch Republic also imported goods from various parts of Europe destined for its own slave trade (Swedish iron, Silesian linen, fire arms from the Southern Netherlands, wine from France, etc.), and exported domestic products used in the slave trade of other nations (cheese, gin, etc.). The former is relatively easy to estimate. We have already seen that the export of goods to West- Africa bound up with the Dutch slave trade amounted to fl.900,000, and have estimated that approximately three quarter of these cargoes were brought into the Dutch Republic from other parts of Europe, which has to be discounted by one third to account for lower prices of acquisition, making a total of fl.445,500. It is impossible to reconstruct at this point how much of the cheese the Dutch exported to France, or the gin exported to England was subsequently used in the slave trade, but it seems reasonable to estimate this at no more than fl.500,000.

Trade to different regions in Europe

One final preparatory step before we can apply the model of Van Zanden and Van Leeuwen to these overall estimates for the size of the different components of slave-based trade, is to differentiate within the European side of this trade between three large streams: trade through the Sound with Northern and North-Eastern Europe; the river trade, mainly directed to the German hinterland via the Rhine; and the trade with the rest of Europe over sea. The reason why we apply these very large container categories, is that Van Zanden and Van Leeuwen calculated the contribution of trade and shipping to GDP on the basis of weighted measures for these specific routes. We have subdivided the different European streams of goods under the following, slightly simplifying assumptions:

  1. Imports of goods produced in other European Atlantic Empires through European ports have all been headed under the rubric ‘rest of Europe’. Only a tiny proportion of goods imported from Danish ports might be mislabeled by doing so.
  • Half the goods imported from Europe for export to the Dutch Atlantic colonies have been assigned to the Sound, the other half to the rubric ‘rest of Europe’. The same has been done for European goods used in the slave trade.
  • For the division of re-exports over the three different branches of European trade, we could use export data compiled by Gerhard de Kok on the basis of custom records for Amsterdam and Rotterdam in the years 1753 and 1790. Taking the average between the two to represent exports in 1770, we assume the following proportions:

Sugar: Rhine 71%, Sound 27%, Rest 2%

Coffee: Rhine 61%, Sound 37%, Rest 2%

Tobacco: Rhine 24%, Sound 52%, Rest 24%

Other lesser trade goods have been subdivided following the same proportions as tobacco.

  • All exports of domestic goods for the slave trade of other nations have been estimated to have gone to the ‘rest of Europe’.

Table 3 summarizes the results of our calculations thus far.

Table 3 Total value of slave-based commodity trade Dutch Republic in millions of guilders, 1770

 ImportExportTotal Import + Export
Total direct Atlantic18.26.925.1
Rest of Europe12.10.612.7
Total indirect European13.818.432.2
Total import + export32.025.357.3

From total trade flows to value added for shipping and international trade

One way to calculate the contribution made by this large sum of fl.57.3 million to Holland’s GDP would be to estimate the proportion of this trade that was based in Holland as opposed to the rest of the Dutch Republic, calculate value added on the basis of a value-chain approach for all the different trade goods involved subtracting inputs and outputs to avoid double counting or counting non-domestic activities, and relate the total that is thus acquired to the total GDP of Holland of fl.177 million estimated by Van Zanden and Van Leeuwen.

However, as explained extensively in the main text of this article, in our eyes this procedure would be a partial retreat back into a naïve approach. Since the method of Van Zanden and Van Leeuwen relies on using benchmark figures to adjust sectoral proportions, related to a total figure for the GDP that is interpolated from known figures for 1504-1510 and 1807, it would create serious distortions to arbitrarily use different figures for one segment of Holland’s trade without recalculating all other parts. Therefore, we believe that following the methodological assumptions of Van Zanden and Van Leeuwen and relating our own figures to their benchmarks following their methodological assumptions will produce the most reliable estimates. To relate our own 1770 estimates for the total size of Dutch slave-based trade flows to Van Zanden and Van Leeuwen’s total value added in the trading sector, we have used the following procedure:

Step 1

Based on our calculations on the size of slave-based trade to and from different regions (summarized in Table 3), we calculated the proportion of slave-based trade of the total trade with the different trading areas distinguished in Van Zanden and Van Leeuwen’s model (Atlantic, Sound, Rhine, Rest of Europe). To calculate which proportions of the total trade for these routes were slave-based, we have used De Vries and Van der Woude’s trade estimates for the 1770s shown in Table 1, except for the Atlantic trade which we have re-estimated above for the year 1770 specifically. Doing so gives us the following proportions (p) of slave- based imports and exports on the four relevant routes: pATL = 0.984, pSND = 0.197, pREST = 0.099, pRIV = 0.393.

Step 2

We used these proportions (p) to relate our estimates of slave-based activities per trading route to the total value of trade on the different trading routes that forms the basis for Van Zanden and Van Leeuwen’s GDP calculation. By taking this second step, we make sure that we follow the same assumptions that were followed in this model when isolating the output of the trading and shipping sector from the total value of trade streams calculated on the basis of end prices of goods on the Dutch market (which still contain the value added in the regions in which these goods were produced). The total size of the different net trade-flows TF for the Dutch Republic used in their model, subtracting prior inputs, is as follows:

TFATL (Atlantic trade):                         fl.20.85 million

TFSND (Sound trade):                            fl.32.14 million

TFREST (Europe rest):                            fl.37.41 million

TFRIV (River trade):                              fl.43.08 million

The size of the slave-based trade flow, when related back to the figures of Van Zanden and Van Leeuwen, is given by the formula p . TF.

We are well aware these totals depend on many assumptions, quite a few of which are based on calculating steps that remain implicit in the published data series and methodological annex that accompany Van Zanden and Van Leeuwen’s original article.

Starting from the various extant estimates of the total size of trade measured in Amsterdam bourse prices presented in Table 1, it is clear that Van Zanden and Van Leeuwen assigned smaller weight to the trade for their category ‘Rest of Europe’ than the gross size of this trade flow would seem to suggest, and must have started from a far larger gross size of the river trade than is usually assumed.21 On the other hand, their adjustment factors to subtract inputs from the gross trade flow for the Sound trade are slightly below what we would expect to see, although admittedly these expectations are largely based on price differentials between wholesale and retail trade within the Netherlands and on import and export prices in Amsterdam, rather than prices at which merchant bought and sold commodities abroad used by Van Zanden and Van Leeuwen. Furthermore, Van Zanden and Van Leeuwen did not

21 Indeed, recent data on the growth of the trade between the Dutch Republic and the German hinterland show such an adjustment to be necessary. U. Pfister, ‘The quantitative development of Germany’s international trade during the eighteenth and early nineteenth centuries’, Revue de l’OFCE 140:4 (2015) 175- 221.

include any contribution to GDP from the substantial shipping through the river Rhine, instead calculating the contribution of international shipping only on the basis of the sea trade only, but the relatively high proportion of value added in international trade on this route might compensate for this. By and large, we accept these assumptions as necessary parts of the model, especially since the potential overestimations and underestimations that flow from it by and large cancel each other out. Under step 4, we examine the question of potential underestimations and overestimations stemming from the application of this model more closely.

Step 3

The net trade flows form the basis on which Van Zanden and Van Leeuwen calculated the value added in international trade and shipping. They did so on the basis of specific selections of trade goods, that of course do not correspond neatly to the mixture of commodities that we have studied. We therefore have chosen to reconstruct composite weights for each route, working backwards from Van Zanden and Van Leeuwen’s totals while making some minor adjustments for irregularities in the data. The resulting weights are presented as proportions of the net trade flows TF. Finally, all calculations so far have been done on the basis of figures for the trade flows to and from the Dutch Republic as a whole. Van Zanden and Van Leeuwen in their model have used the admittedly very rough measure of an unchanging share of Holland in Dutch trade for each of the different routes, that we express here with the Greek letter γ.

Table 4 Weighing factors used by Van Zanden and Van Leeuwen

 Value added in trade as proportion of TF, assumptions vZ and vL (X)Value added in shipping as proportion of TF (Y)Share of Holland in trade of Dutch Republic (γ)
Europe: Rest0.3010.0550.75
River trade0.15000.8

For each route, the value added in international trade will thus be given by the simple formula

p . TF . X . γ, and the value added in international shipping by the simple formula p . TF .Y . γ. On the basis of the figures given above, we estimate the contribution of slave-based international trade to the GDP of Holland to be:

Atlantic trade: fl.5.95 million; Sound trade: fl.1.81 million; Rest of Europe: fl.0.83 million; Rhine trade: fl.2.03 million;

Bringing the total value added of slave-based international trade to fl.10,62 million.

Following the same procedure, we estimate the value added from slave-based international shipping to be:

Atlantic trade: fl.2.21 million; Sound trade: fl.0.35 million;

Rhine trade: not included in the model (subsumed under international shipping) Rest of Europe: fl.0.15 million,

Bringing the total contribution of slave-based international shipping to fl.2.71 million.

Step 4

Step 1 to 3 give us the total value added in international shipping and trade following the assumptions of the model of Van Zanden and Van Leeuwen, and using composite adjustment factors to adapt gross trade flows to net trade flows per trade route. However, our starting point for these calculations were source-based estimates for the total value of slave-based imports and exports. Our final step is to go back to these original numbers, and verify whether implementing the various weighting factors actually leads to credible results. In

order to do so, we pretended that the value added in trade and shipping was derived directly from the total value of trade, without the intermediary steps dictated by the model.

Calculating the value added in both branches as proportions of the gross trade flows gives us numbers that can be meaningfully compared to what the sources tell us about the profitability of international trade and shipping in this period. Table 5 gives these proportions (note that in order to compare to the gross value of trade for the Dutch Republic as a whole, the figures given in step 3 have to be divided by γ).

Table 5 Value added in international trade and shipping expressed as percentage of gross trade flows on each trade route

 Total value of the trade (million fl.)Value added in int. trade (million fl.)%Value added in shipping (million fl.)%
Europe: Rest12.71.190.22
River trade11.82.52200

It is obvious from Table 5 that the question whether this model gives a realistic perspective on value added in slave-based trade and shipping stands or falls with the proportions for Atlantic trade. Fortunately, the robustness of the model for this branch can be tested with an unusual amount of precision, due to the availability of the very detailed accounts for a very large number of voyages in the MCC records. Gerhard de Kok has reconstructed the accounts for all Atlantic voyages of the MCC, presented in Annex B of his dissertation.22 The completeness of these records, based on over hundred voyages between 1730-1795, allows us to do something that is very rare indeed: test our outcome for the most important component of our GDP calculation on a contemporary source, using exactly the same measures that we applied in our model. The results are presented in Table 6. The value of outgoing goods (exports for the slave trade) and incoming goods (imports from the West-African coast and West-Indian plantation goods) are both measured in current prices paid for those goods in the Dutch Republic itself, just as in our overall estimates for the size of the various trade flows.

22 G. de Kok, Walcherse ketens. De trans-Atlantische slavenhandel en de economie van Walcheren, 1755-1780, unpublished dissertation, Leiden University 2019, Annex B.

Value added per voyage is represented here by net profits, sailors’ wages and bonuses, the contribution paid by the MCC to Dutch West India Company (WIC) (a redistribution of value added between commercial companies), and insurance fees minus damages claimed for the profits drawn from these voyages by insurance companies.23 Since the MCC was both trading company and shipping company at the same time, the value added in trade and shipping is taken together.

23 Van Zanden and Van Leeuwen do not include a separate post for the profits of insurers in their GDP model, thereby assuming this was part of the value added in trade. We are aware that insurers made some domestic costs apart from the sums paid in damages, but on our totals, these sums are negligible.

Table 6 Value added in trade and shipping on MCC voyages, 1732-1693

PeriodNumber of voyagesTrade goods for W-Africa (Dutch prices, fl.)Goods imported from W- Africa and W-Indies (Dutch prices, fl.)Total gross TF MCC (Dutch prices, fl.)Net profits or losses on voyagesWages plus bonusesContribution to WICInsurance premiums minus damagesValue added on gross TF (per centage)

The period that includes the year 1770 show a percentage of value added of 41.5, slightly above the number inferred by us for the Atlantic trade in Table 5. In fact, the five MCC voyages for the single year 1770 were all highly profitable. Basing ourselves on that year alone, we would get a value added of 56 per cent of the gross trade flow. This result is all the more notable, as the MCC was primarily a slave-trading company, with trade in slave- produced goods always coming second. The Dutch literature, as much of the international literature, generally assumes the slave trade to be one of large windfalls and even larger losses, a reality reflected in the accounts presented above in the volatility of profits and losses. The bilateral trade in Atlantic goods, while contributing less to the value added in shipping, is generally assumed to have been much more stable and profitable. This bilateral trade formed the majority of Dutch Atlantic voyages. About 80 per cent of Dutch ship traffic with Suriname in the 1770s was bilateral trade (an annual average of 59.6 bilateral voyages, against 14.6 triangular voyages).24 Therefore, the proportion of value added by the MCC in shipping and trade can be taken as strong confirmation of the model applied by us.

What about the other trade routes? We have already made a remark under step 2 about the relatively low value added captured in comparison to the size of the gross trade flow in the trade with the category that Van Zanden and Van Leeuwen have named ‘rest of Europe’ (including France, Britain and the Mediterranean), and the relatively high proportions in the Sound trade. Adjusting the proportion of the value added in the Sound trade downward to 15 per cent, while readjusting the value added in the trade with the rest of Europe upward by a

24 J. Postma, ‘Suriname and its Atlantic connections, 1667-1795’, in: J. Postma and V. Enthoven, Riches from Atlantic commerce. Dutch transatlantic trade and shipping, 1585-1817 (Leiden/ Boston 2003) 287-322, 295.

similar proportion, also to 15 per cent, would lead to a net result just above the total given by our model (an upward adjustment of fl.150,000). We therefore stick to the conclusion that the potential over- and underestimations for these two trade flows cancel each other out, and decide not to make any adjustments. Finally, for the Rhine trade, we have seen that Van Zanden and Van Leeuwen apply a proportion of 15 per cent value added in trade and shipping for this route. However, since they assume a TFRIV that is substantially larger than the total inferred from the existing estimations, the inferred proportion as calculated in Table 5 comes out higher than this 15 per cent. Since we have started our calculations not from projections of the size of the trade on this route based on a model, but from the actual size of the trade that can be deferred from export figures for sugar, coffee and tobacco, there is in principle no reason for such an upward adjustment. We therefore would deem it more responsible to stick to the proportion of 15 per cent value added in international trade. On the other hand, not calculating any value added for shipping on the Rhine trade presents quite a substantial under-estimation. Once again, we can assume that these two cancel each other out.

2 Shipbuilding

We have considered a variety of methods to approach the total size of value added in the shipbuilding sector that was derived from slave-based activities. Van Zanden and Van Leeuwen calculate the value added in the shipbuilding industry on the basis of the estimates of fleet size that were compiled earlier by Van Zanden and Van Tielhof, the underlying data on the number of ships active on various trading routes once again going back to Van der Oudermeulen.25 Of course, numbers of ships do not tell much about shipbuilding requirements (replacement and repair), unless the differences in ship-size between merchant- men sailing on European and trans-Atlantic routes are factored in, as well as the differences in usage. Van Zanden and Van Tielhof produced a measure that consisted of the numbers of ships active on different routes, an estimate for the average size of the ships sailing on those routes (in last), and the distance of the routes in kilometres. Since their calculations for the value added in shipping are based on this measure, we can assume that the share of slave

25 J.L. van Zanden and M. van Tielhof, ‘Roots of growth and productivity change in Dutch shipping industry, 1500-1800’, Explorations in Economic History 46 (2009) 389-403, especially online annex.

based value added in the total value added contributed by the shipping sector also reflects the claim that slave-based activities laid on Holland’s shipbuilding capacity. This share (based on the calculations presented above) was 31.7 per cent. With the total value added in shipbuilding, Holland’s most important industry, estimated at fl.3.1 million, this brings us at a total of fl.984,000 depending on slave-based trade.

3 Sugar industry

As argued above, the large Dutch sugar refining industry in the 1770s was still completely dependent on imports of raw sugar produced in the Atlantic. With 98 per cent of all imports produced by slaves in the West Indies (the sugar imports from the East Indies were not very significant at this point), and no replacements at hand, the output of this branch of industry was fully dependent on its connection to slavery. We therefore find it justified to classify almost all (98 per cent) value added in the sugar industry as slave-based. Relating this to the figures of Van Zanden and Van Leeuwen gives a total value added of fl.682,420 in this sector. This is a realistic estimate. According to Reesse, 150 sugar refineries were active in Holland in the year 1771, employing about 4,200 workers in total.26 If we assume that all of these workers received a yearly wage of fl.180 (the tariff for unskilled labour), income from wages alone would have amounted to fl.756,000. Including profits and rents, it is more likely that the value added from sugar refining amounted to around fl.1 million per year, but we have used the above mentioned more conservative figure in order not to lose the connection to Van Zanden and Van Leeuwen’s benchmark estimates.

4 Domestic trade and transport, Domestic industries (excluding sugar and shipbuilding), Agriculture and fisheries

26 J.J. Reesse, De suikerhandel van Amsterdam. Van het begin der 17e eeuw tot 1813 (Haarlem 1908) 58.

Van Zanden and Van Leeuwen only explain how they calculated value added for domestic transport. They do not do so for domestic trade. However, we think it is possible to come to an estimate of the proportion of value added of domestic transport, trade and processing taken together. For most slave-based domestic activities, it is not possible to separate out these element. We therefore in most cases will have to make do with assumptions on the combined contribution of these activities, taking care not to include elements of the total revenue that have been subsumed elsewhere, primarily under international trade, and realizing that this part of our calculation remains somewhat more speculative.

The first component of slave-related domestic trade and transport consisted of the inland distribution of slave-produced sugar (raw and refined), coffee, and lesser slave-produced trade goods.

  • For coffee, Tamira Combrink calculates that in 1770, the total value of slave-based coffee imports stood at fl.10.2 million, while coffee exports valued fl.7.5 million, leaving fl.2.7 million for inland consumption. Based on a (admittedly, very limited) amount of observations of prices for coffee retail, she calculates a total value added for roasting, inland trade and transport of 47 per cent on top of the bourse price.

Factoring in spoilage and other losses accrued in the process of selling the coffee, it seems safe to assume that inland traders, transporters and roasters received 33 per cent on top of wholesale prices of all the coffee on the domestic market, making for a total sum of fl.891,000, of which we estimate 50 per cent to have consisted of wages and profits for the trading houses, inland transporters, retailers, etc. This sum for the Netherlands as a whole can then be transferred to an amount for the province of Holland based on rough population estimates (40 per cent), assuming that per capita consumption of coffee in urbanized Holland was as high as in the rest of the Netherlands (which is probably an underestimation for Holland), leading to a total of fl.178,000.

  • For sugar, Tamira Combrink calculates that in 1770, slave-based imports of raw sugar valued fl.11.3 million, while slave-based sugar exports totalled fl.10.1 million.

However, import and export values do not yet give a figure for domestic consumption, due to the fact that most sugar underwent industrial refining, which added substantially to the value of the product, while at the same time resulting in considerable weight loss between raw material and end product. Taking into account both factors, Combrink estimates the value of sugar traded and consumed inland at

fl.4.3 million. On top of the value added in refinery (which we have factored in under a different post), Combrink estimates 17 per cent of consumer prices going to retail as a whole, including transport and domestic trade. Once again estimating half of this sum to have consisted of wages and profits, the total value added in the domestic sugar trade can be estimated at fl.366,000. This sum for the Netherlands as a whole can then be transferred to an amount for the province of Holland following the same assumptions as under coffee, leading to a total of fl.146,000.

  • Apart from coffee and sugar, the Dutch imported slave-produced tobacco, indigo, cotton and cacao. Most of the tobacco imported in the Netherlands came from Virginia and Maryland. Part of this was processed for re-export, and another part was processed for domestic consumption. For lack of more reliable data, we estimate a total contribution in value added for tobacco on the basis of what we know about the size of the tobacco processing sector. According to one contemporary estimate, Rotterdam as the main centre of colonial tobacco imports at the end of the eighteenth century employed 3,500 workers in the tobacco processing industry. These workers processed inland tobacco as well as colonial tobacco, at a proportion of 1:2.

Roessingh questions this figure, so to be on the safe side it might be better to take this as the total number of workers employed in tobacco processing in the whole of Holland.27 If we conservatively estimate the value added in this branch of industry as

0.33 times the number of workers it employed at a yearly wage of fl.180, tobacco processing added fl.210,000 to Holland’s GDP. For lack of data, we make a guestimate that the inland processing, transport and retail trade of all lesser colonial goods combined added fl.300,000 to the GDP of Holland.

The second component of slave-related domestic production, trade and transport consists of the proportion of the trade goods exported to the Atlantic colonies that were produced in Holland, as well as the domestically produced goods used in the Dutch slave trade and the slave trade of other European nations. Under international trade, we have already presented our estimates for the total size of these trade flows: fl.1.5 million in products produced in the Dutch Republic for the Atlantic colonies, fl.225,000 in domestically produced goods for the Dutch slave trade, and fl.500,000 in domestically produced goods for the slave trade of other nations. Adapting trade flows to and from the Dutch Republic to flows to and from Holland, we use the values γ mentioned in Table 4, giving a total of fl.1.17 million in goods exported

27 Roessingh, Inlandse tabak, 396.

from Holland to the Atlantic colonies, and fl.550,000 exported from that province for the slave trade. However, since this is calculated on the basis of end prices in export that already contain a value added element, we have to deduct roughly 60 per cent in order to avoid double counting. If the value added in domestic production, trade and transport amounted to 80 per cent of the pre-export value of these goods (a high proportion that reflects the fact that the entire value chain for these goods was domestic), they contributed fl.550,000 to the GDP of Holland.

The third component of the value added in the domestic sector is formed by victuals and other supplies to the merchant ships active in slave-based trade. This can only be calculated on an extremely tenuous basis. Many, though certainly not all, of the victuals and other goods necessary for the equipment of transcontinental voyages were produced locally. Apart from domestic trade and transport, these also contributed to the agrarian sector and food-processing industries such as bakeries and brewers. Just like in the case of the domestically produced goods exported to the colonies, only very rough measures are available. The MCC provides the best proxy. Gerhard de Kok has reconstructed the accounts for all MCC voyages, 30 of which took place in the 1770s. On average, fl.50,211 per journey was spent on operational costs (the figures excludes the costs of shipbuilding, masts and rigging, etc., thereby avoiding double counting with the shipbuilding sector). Of these, fl.17,471, or 35 per cent of the operating costs consisted of victuals and other necessities.

Sailors’ wages are excluded from this total, since in the approach of Van Zanden and Van Leeuwen they belong to value added in the shipping sector. Using Van der Oudermeulen’s 1780 figures for trans-Atlantic voyages, and adjusting these for the smaller size of Atlantic trade in 1770 according to the proportion mentioned in Table 2, we estimate 163 slave-based Atlantic voyages to have taken place that year, which would have required 163.17,471 = fl.2.85 million in victuals, 78 per cent of which were destined for voyages leaving from or arriving in Holland. If 75 per cent of the inputs were produced locally in Holland (a realistic proportion given the dominance of domestically produced goods in sailors’ rations), with 80 per cent of their total value counted as value added in domestic production and agriculture, trade and shipping, this adds another fl.1.33 million to the GDP of Holland.

The total value added in agriculture, industry (excluding shipbuilding and sugar), inland trade and shipping from slave-based activities in this way comes at fl.2.5 million.

5 Banking and related financial services

Interest payments received from abroad do not form part of the GDP (they are included in a different measure for national accounts, the GNI). Therefore, the sizeable but speculative business of mortgaging for the plantation sector remains largely outside of our calculations. However, the domestic activities of banks, such as providing financial services that enabled foreign loans to and transactions with the plantation sector, do add to the GDP via the service sector. Van Zanden and Van Leeuwen calculate the total value added in the banking sector on the following basis:

  • The total size of inlays at the end of the year in the Amsterdam Exchange Bank are taken as an indication of the activities in international banking. For the year 1770, they give the number of fl.13,001,254. Van Zanden and Van Leeuwen calculate the value added of these banking activities as 2 per cent of this amount.
    • All the IPO’s undertaken by Amsterdam bankers in this year, totalling fl.13,015,000. ‘It is estimated that 5 per cent of the sum of the IPO was earned by the bank and its network of distributors’.

Under these assumptions, Van Zanden and Van Leeuwen estimate the value added of the banking sector in 1770 at fl.910,775 (see dataset Banking-sector).

For our estimate of the value added from slave-based banking activities, we base ourselves on the size of newly issued Atlantic plantation loans alone, thereby avoiding the risk of double counting arising from the fact that the directors of these loans frequently also handled financial transactions between Suriname and Amsterdam. Alex van Stipriaan estimates that between 1765-1772, Dutch West-Indian negotiation funds on average placed

5.8 million guilders per year in new loans.28 Van de Voort gives a total sum of fl.7,312,000 for the year 1770. He calculates that 81.0 per cent of these loans were arranged by funds based in Amsterdam.29 Since Van Zanden and Van Leeuwen make their calculations on the basis of IPO’s undertaken by Amsterdam bankers, it seems reasonable to use Van de Voort’s

28 A. van Stipriaan, Surinaams contrast. Roo6ouw en overleven in een Caraïbische plantagekolonie 1750-1863

(Leiden 1993) 218.

29 J.P. van de Voort, De Westindische plantages van 1720 tot 1795. Financiën en handel (Eindhoven 1973) 102- 103.

figure for Amsterdam, rather than one for Holland in its entirety, to come to our estimate. As to the 5 per cent used to calculate the value added for bankers and their network from IPO’s, it is reasonable to assume that at least before the crash of the ‘negotiation system’ of 1771- 1772, this is reasonable for the income in the banking sector from the issuing of new West- Indian loans as well. For courtage alone, many negotiation funds allowed the fund directors 1.5-2.5 per cent of the total mortgage sum. Furthermore, directors could earn substantial sums from fees on the sale of plantation products and from arranging insurance on shipments of plantation goods (the value added of insurance activities in general are factored in under financial services and trade and shipping, which is why they do not appear as a separate post in our calculation). Finally, as Bram Hoonhout has shown, even when plantation loans accrued losses, it is unlikely that these were accrued primarily in the banking sector, given the position of power of administrators of the newly issued funds within the funding network.30

On this basis, we can calculate the value added from plantation loans for the banking sector of Holland at 7,312,000 . 0,81 . 0,05 = fl.296,136 (an underestimation, since it assumes that all financial activities in Holland took place in Amsterdam alone).

6  Notaries

Like the financial sector, notaries also performed services that were indispensable for the functioning of the plantation economy, and that were part of Holland’s domestic economic activities. Van Zanden and Van Leeuwen estimate the contribution of notaries and book traders to the GDP of Holland at slightly over 1 per cent. They arrive at this estimation by estimating the number of active notaries in Holland, applying the relative proportion of notaries to book traders derived from the Quotisatie of 1742 and an estimation of the salaries for both professions. Since transactions connected to Atlantic slavery were such a large part of business transactions that appeared before notaries at the end of the eighteenth century, it is fair to say that part of the income of notaries in Holland was directly dependent on this sector. Which part exactly is of course difficult to measure. Until the Amsterdam notarial records have been fully digitized, we will have to make do with a rough approximation. Cátia

30 B. Hoonhout, ‘Subprime plantation mortgages in Suriname, Essequibo and Demerara, 1750-1800. On manias, Ponzi processes and illegal trade in the Dutch negotiatie system’, MA Thesis Leiden University, 2012.

Antunes and Filipa Ribeiro da Silva have compiled a database of commercial contracts elaborated by Amsterdam notaries from 1580 through 1776. Out of 16,600 commercial contracts, 3,732 pertained to the Atlantic world, or 22.4 per cent.31 Based on the proportion between notaries and book traders found in the Quotisatie, taking into account that 1) Atlantic contracts in this figure exclude contracts related to the European branches of slave- related commodity trade; 2) the proportion of slave-based activities in commercial activities as a whole was largest at the end of the period examined by Antunes and Ribeiro da Silva; 3) handling commercial contracts formed a large part of notaries’ activities; and 4) the proportion of notarial activities directed towards slave-based sectors was higher in Amsterdam than in the rest of Holland, we come to the guestimate of 12.5 per cent of all value added in this sector being accrued in slave-related activities. Given the very small size of value added derived in this way, using either more or less conservative estimates will not lead to major differences in the total proportion of slave-based activities in Holland’s GDP.

7 Military and naval expenditure

It might be counter-intuitive to include military and naval expenditure in the GDP. From the perspective of an individual merchant, both represent costs, not gains, just like other state expenditure. However, from the standpoint of an economy as a whole, both military expenditure and state expenditure belong to the output of the nation, provided of course that taxes are not included as income in the other branches of the economy. Van Zanden and Van Leeuwen calculated that each of these two branches comprised around 3.5 per cent of Holland’s economy. More than in the East Indies, defence of the Atlantic colonies and trade routes against imperial rivals and slave resistance was shared between the trading companies and the state. Military outlays for this purpose formed part of Holland’s GDP. Van Zanden and Van Leeuwen base their calculation for the value added by the army and navy on the size of military expenditure by the province of Holland, plus the size of customs, which formed the independent source of income for the Admiralty Boards. They assume that 90 per cent of all military expenditure was value added, consisting of wages paid to soldiers and sailors and

31 C. Antunes and F. Ribeiro da Silva, ‘Cross-cultural entrepreneurship in the Atlantic. Africans, Dutch and Sephardic Jews in Western Africa, 1580-1674’, Itinerario 35:1 (2011) 49-76, 50.

domestic value added of industries supplying military equipment. If we accept this method of calculating, the proportion of value added that derived from the defence of interests in slavery can be gauged from estimating the proportion of military outlays directed to the Atlantic world. The protection of the West-Indian colonies themselves fell under the prerogative of external bodies such as the WIC and the Society of Suriname. Therefore, for the period under discussion only the subsidies paid out of the general means for overseas defence (fl.77,600) plus outlays by the Holland Admiralty Boards on convoying in the Western hemisphere (and related shipbuilding and supply) should be counted as such.32 No figures for the distribution of naval outlays in 1770 are available, but basing ourselves on figures for Amsterdam for an earlier period of the eighteenth century, we estimate that 33 per cent of the total naval expenditure on operations at sea of Holland in the peace-year 1770 (about 60 per cent of total Admiralty Board expenditure which stood at almost exactly fl.3 million) was directed to the protection of Atlantic trading routes.33 This leads to an upper bound estimate of a value added of fl.602,066. However, we recognize that this might be a serious overestimation. Naval expenditure in particular depended to a very high proportion on foreign imports of wood, hemp, and other necessities, as well as extraordinary expenditure on victuals and other supplies abroad, which do not add to Holland value added. To avoid overestimations, we therefore propose to use a factor 0.6 where Van Leeuwen and Van Zanden used a factor 0.9. This leads to an adjustment of the value added in this sector to fl.401,378.

8 Summary

Based on these figures, using conservative estimates, refraining from the use of multiplier factors and consistently relating all our results to the benchmark figures used by Van Zanden and Van Leeuwen, we conclude that the total contribution of slave-based activities to the GDP of Holland was 10.36 per cent. Of this 10.36 per cent, 7.53 percentage points were located in international trade and shipping, leaving 2.83 percentage points to other sectors of Holland’s economy. These results are summarized in Table 7 below.

32 R. Liesker and W. Fritschy, Gewestelijke financiën ten tijde van de Republiek der Verenigde Nederlanden. Deel IV: Holland (1572-1795) (The Hague 2004) 406.

33 Total expenditure of the Holland admiralty boards taken from W. Veenstra, Tussen gewest en Generaliteit. Staatsvorming en financiering van de oorlog te water in de Republiek der Verenigde Nederlanden, in het bijzonder Zeeland (1586-1795), Unpublished dissertation VU Amsterdam 2014, 246, 249 and 252. Proportions taken from P. Brandon, War, capital, and the Dutch state (1588-1795) (Leiden/ Boston 2015) 113 and 132.

Table 7 Contribution of slave-based activities to the GDP of Holland, 1770 (x1000 guilders)

SectorSector totalBranchBranch totalSlave-based totalSlave-based total as % of branch totalSlave-based total as % of GDP
Agriculture and fisheries19,919.6     
  Of which: shipbuilding3,071.1597431.740.55
  Of which: sugar refinery696.3968298.000.39
  Of which: International trade42,629.610,62024.916.00
  Of which: International shipping8,537.942,71031.741.53
  Of which: Banking and financial services910.7829632.510.17
  Of which: notarial services1,777.9522212.500.13
  Of which: Army and Navy6,393.763345.230.19
Slave-related value added that falls under various sectors Domestic production, trade and shipping 2,500 1.41
Total177,069  18,340 10.36
  • From GDP of Holland to Dutch GDP

We can use this more detailed estimate of the GDP of Holland to calculate the share of slave- based activities in the overall Dutch GDP. First of all, this requires inferring Dutch GDP from Holland’s GDP, using the known proportion for 1807 (37.5 per cent), and adjusting this to 40 per cent for the fact that Holland’s trade-dependent economy in all likelihood suffered more from the wars and occupation following 1795 than the Dutch economy as a whole. This leads to a GDP of the Dutch Republic of fl.442.8 million.

For some of the largest sectors for which we calculated value added by slave-related activities, the figure for Holland was derived from a total figure for the Dutch Republic in the first place (international shipping and trade; domestic processing, shipping and trade in coffee and sugar). Calculations for the other sectors have been made on the basis of the following conservative methods:

  • Shipbuilding: 80 per cent of value added in Holland (the other 20 per cent reflecting Zeeland’s continued importance in Atlantic shipping and the slave-trade).
    • Financial services: all value added concentrated in Holland.
    • Notarial services: 80 per cent of value added in Holland (reflecting Zeeland’s continued importance in Atlantic shipping and the slave-trade).
    • Navy: 90 per cent of operational expenses for the navy in 1770 done by Holland Admiralty Boards (based on detailed figures compiled by Wietse Veenstra).
    • Sugar industry: all value added concentrated in Holland.
    • Other domestic agriculture, industry, trade and shipping: sugar and coffee given above, Atlantic export products 30 per cent produced domestically (slightly higher than the 25 per cent used earlier to include trade between provinces), supplies to the Atlantic merchant fleet given above.

Taken together, this leads us to a total of 5.2 per cent of the entire Dutch GDP of 1770 being slave-based.

10 Development of the slave-based contribution to GDP of Holland

How representative is the year 1770? No extensive calculations have been made due to the paucity of trade figures on which applying our model for 1770 would rely. We therefore had to make do with a more tentative approach. As is clear from the calculations presented above, the contributions made by four of the largest posts in our estimation (international trade, international shipping, shipbuilding, and domestic production, trade and shipping) were heavily dependent on the total value of slave-produced sugar and coffee imported to the Netherlands, coming through the Dutch Atlantic colonies (either as direct exports, or as re- exports of coffee and sugar produced in the French West Indies) and France. On the basis of more or less complete import data for sugar and coffee from these two areas for most of the years between 1738 and 1750, 1761 and 1771, and 1775 and 1779, we were able to make a weighted index (using current prices, and applying the weighting factors derived in Table 5). This of course is not a precise measure. For one thing, it is not necessarily true that these factors remained constant throughout this period. Nevertheless, by way of approximation these two indices for trade and shipping in our view work well enough to test whether the year 1770 was an outlier, and how it fit longer-running trends. We have comprehensive data on the annual value of sugar and coffee imported from the Dutch West-Indies for 24 years in the period 1738-1779, leading to the index figures presented in Table 8. From the 1770 calculations, we have extrapolated totals for international trade and domestic production, trade and shipping (using the trade index) and for international shipping and shipbuilding (using the shipping index). For shipbuilding, we have introduced an intermediate step of calculating the proportion of the total slave-based shipping volume derived with the aid of our index to the total value added in shipping each year, to reflect the changing composition of the Dutch merchant fleet.

For several of the branches that contribute to our total estimation, it is not necessary to apply one of these indices. This is true for the sugar industry, the army and navy, and notaries, where we deem it more consistent to apply the proportion found above to Van Zanden and Van Leeuwen’s estimates of their contribution to GDP. For banking, the speculative boom in plantation mortgaging has to be factored in, which started in the 1750s and for which 1770 was a peak year. We have done so by applying the proportion we found earlier for 1770 for the boom years 1764-1772 only, estimating a constant value of fl.100,000

for 1761-1762, and setting the contribution of this branch in the pre-1761 and the post-1772 period at 0, which of course is an underestimation.

Table 8 Index for value added of sugar and coffee imported from the Dutch West Indies and France in trade and shipping (1770=100)


Sources: Trade figures compiled by Gerhard de Kok and Tamira Combrink. Suriname: J. Postma, Dutch shipping and trade with Surinam, 1683-1795. DANS; Berbice: K. Kramer, ‘Plantation development in Berbice from 1753 to 1779. The shift from the interior to the coast’, Nieuwe West-Indische Gids 65:1/2 (1991), 394-395; J. de Hullu, ‘Memorie van den Amerikaanschen raad over de Hollandsche bezittingen in West-Indie in Juli 1806’, West-Indische Gids 4:1 (1923); Essequibo and Demerara: H. Bolingbroke, A voyage to the Demerary (London 1807), Appendix I, 397; NL-HaNA, WIC 1136, cargo manifests 1790; Curacao: Van der Voort, Westindische plantages, 260-261; Klooster, Illicit riches, 234, appendix 9; St. Eustatius: Klooster, Illicit riches, appendix 5, 226-227; France: Van der Voort, Westindische plantages, 260-261; France: TOFLIT18 database, (accessed 31-05-2019).

The overall results are presented in Table 9 and Figure 1. We have left out the year 1779, which is an outlier due to the exceptionally high value of sugar and coffee imports for that year. Figure 1 shows the steady growth of the importance of slave-based activities for the Dutch economy during the middle decades of the eighteenth century, which fits the picture that is familiar from the literature on the development of the Atlantic sector. Based on these figures, we can conclude that the year 1770 fit the trend for the 1738-1778 period almost perfectly. When comparing only to the 1760s and 1770s, 1770 actually was a below-average year. After 1779, complete trade records are absent, but this does not mean that Atlantic trade collapsed with the exception of the period of the Fourth Anglo-Dutch War. Based on incomplete records, slave-based trade seemed to have resumed at a level commensurate with the period 1775-1778, slightly above our benchmark year 1770, a situation that was only permanently disrupted with the outbreak of the French Revolutionary Wars.

On this basis, we arrive at the time series presented in Table 9 below, with the total contribution of slave-based activities to the GDP of Holland rising from around 5 per cent in the late 1730s to over 14 per cent at the end of the 1770s.

(Grafiek 3 = Figure 1)

Figure 1         Slave-based activities as proportion of the GDP of Holland, using trade and shipping indices based on the development of sugar and coffee imports

173817401742174417461748175017521754175617581760176217641766176817701772177417761778x-as = years, y-as = Holland GDP

Table 9           Calculations for GDP in selected years, 1761-1785, amounts in fl.1000, based on import index and assumptions outlined in text

YearInternationa l tradeInternationa l shippingDomestic production, trade and shippingShipbuildin gSugar refineryBankingNotariesArmy and NavyTotal slave- based value addedTotal size GDP of HollandWeight of slave- based activities in GDP Holland

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