Source Rapport betreffende de defensie van Nederlandsch-Indië , dated April 1892
The defence of the Dutch East Indies was for 1,5 century a huge problem especially lacking the (financial) resources for such a large area. In her report dated 23 April 1892 a commission Kromhout (1) stated that the defence of Java was the most important issue in case of an enemy attack. The navy was to protect as much as possible the ouposts. If the navy was unablle to perform het duty, the commanding officers of the strongholds along the coasts were to retreat. They were unable to defend themselves against modern artillery. The navy was also responsible for defending Java and was to stop an invasion and/or so-called coups-de-main (2) against the cities along the coastline especially Batavia and Surabaya, then Samarang and more or less Cheribon. Main conclusion was that the state of the navy in the Dutch East Indies was completely insufficient. Rear admiral Kruys said that at least 30 ships and vessels were needed including 4 large warships like the Hr.Ms. Koningin Wilhelmina der Nederlanden, a force to be realized within a few years. To make it possible to cruise independently through the archipelago and to perform her war duties there were two operational bases needed, one on West Java and one on East Java with coal depots and repair facilities. Before strengthening the one at Surabaya, East Java, was tfe far more import one on West Java to be established. For the location preferred the commission Batavia [nowadays Jakarta] and Tandjong Priok instead of the Duizend eilanden. A satisfying defence of the island Onrust was out of the question. If was chosen voor Batavia it would be necessary to keep the enemy of a distance of 3 kilometres of the harbour of Tandjong Priok and the coal depots there, if it became a refugee harbour for merchant shipping then was the distance 6 kilometres. Building forts on the coast was in fact no real option and presumable far too expensive. Eartquakes were considered to be a real threat especially in damaging the rotating devices of the armored turrets. Malaria was another large problem for the health demanding a large number of troops to have enough men available, which was also a logistical problem altogether quite expensive. The commision proposal included two floating armoured turrets in the outer harbour of Tandjong Priok.
Such a battery was made of nickel steel and mounted on a iron ship/vessel and of which the non-armoured parts were protected by dams with a wide of around 12 metres. Dams and batteries had to have the same colors to mislead the enemy artillery. To keep the height of the gun barrels above the dam constant was water pumped out or let in with ebb and flow (0,7 metres). Each turret was armed with 2-21cm/8.27” L/35 guns. When building and arming the turrets was a logistical problem to be taken into account. At the navy yard at Amsterdam was a crane with a capacity of 100 tons available, at Tandjong Priok just a crane with 25 tons, above 25 tons was to be lifted at Onrust.(3) Each floating battery was manned by an artillery officer commanding 50 men including 10 artillerists, For letting in of pumping out the water were forced labourers to be used. In times of war were the men to serve just 8 hours making a needed total of 6 officers, 60 artillerists and 240 infanterists.
The costs of one armoured gun turret with front armour, assembly and all needed parts were according tot a non official tender of the representative of the firm Krupp at Essen, Germany 300,000 mark.
Rate of transport costs for the Department of Colonies at Rotterdam or Amsterdam with as destination the Dutch East Indies 55 guilders/ton, weight colli above 8,000 kilo.
Weight each turret 140,000 kilo, transport costs 2 x 140 x 55 (guilders)-15,400 guilders.
Mounting in the Dutch East Indies would be quite expensive was expected
To prevent disappointment was the price in Europe estimated in German marks for the Dutch East Indies estimated in an equal number of guilders
Total price for both turrets was to be 600,000 guilders
For two iron built ships on which the turrets were mounted 650,000 guilders
For the protecting dams 150,000 guilders
Costs of one 21cm/8.27” L/35 gun with carriage delivered by Krupp 100,375 German marks.
Total costs of the defence of Batavia and Surabaya including the turrets at Tandjong Priok was estimated to be 3,000,000 guilders.(4). Despite was the conclusion a few years later, still nothing done.
Notes
1. Members of the commission were:
Major Frederik Jan Haver Droeze (17 July 1847 Vlaardingen, Netherlands-5 January 1909 Dordrecht, Netherlands), member and secetary.
Lieutenant general of military engineering Joachim Hendrik Kromhout (12 June 1835 Lathum, Netherlands-29 July 1897 Klein Avegoor, Rheden, Netherlands), also author.
Vice admiral Gerhardus Kruys (21 August 1838 Vriezenveen, Netherlands-12 December 1902 The Hague, Netherlands), minister of navy between 31 March-21 August 1891 and 1 August 1901-12 December 1902 and Chief Naval Staff 1 September 1891-1 March 1894, member of the Staatscommissie voor de land- en zeemacht since 18 April 1891.
2. The commission was nicknamed coup-de-main commissie. A coupe-de-main is a surprise (fast) attack on small scale for instance against a coastal town. Apparently I used a limited editon of the printed report titled Rapport betreffende de defensie van Nederlandsch-Indië numbering just 13 pages. In the magazine Militaire Spectator 1985-4 is an article of ir. H.T. Bussemaker, “De geloofwaardigheid van de Indische defensie 1935-1941”, published. Bussemaker referred to page 25 of the report a coup-de-main by England of Russian on Batavia. Thomas L. Sturtevant, Quincy, Massachusetts published an article titled “A proposed system of harbor defense”, in the Journal of the United States Artillery, volume V, 1896, p. 173 of a similar harbour defence.
3. Probably referring to the steam crane annex sheerleg Olifant, see on Warshipsresearch.blogspot.com
4. For more literature dealing with the defence of the Dutch East Indies see for instance De Indische Gids, 22e Jaargang, Amsterdam, 1900, p. 202 “De verdediging van Nederlandsch-Indië tegen een buitenlandschen vijand. VI. De oorlogshaven en haar verdediging”. The author mentioned that when the Naval Budget for 1897 was discussed the minster Jhr. Van der Wijck claimed a defence of Tandjong Priok by floating batteries which was very expensive. In 1893 published W.R. de Greve his De verdediging van Nederlandsch-Indië. And finally a report of a commission appointed in 1889 “tot het uitbrengen van een advies omtrent de vraag: “of de bestaande indeeling der zeemacht in den Nederlandsch Oost-Indischen Archipel, overeenkomstig het Koninklijk Besluit van 16 November 1866 No. 80 (Indisch Staatsblad 1867 No. 56), al dan niet behoort te worden bestendigd?”, published in 1891.
