The shipyard De Schelde
The shipyard De Schelde was one of the bigger yards in The Netherlands. The yard worked on both civil and military orders. It was one of the most important yards for navy orders (end would remain so until recently). The Germans shared the Dutch interest in the yard and had no plans whatsoever to damage the facility. It was all to useful for their own plans for the near future.
The ships under construction
In May 1940 de Schelde had quite a number of navy orders in variable stages of construction. Two heavy destroyers [Dutch ship-design of 2,240 tonnes displacement that was something in between a light cruiser and heavy destroyer], the HrMs Isaac Sweers and the HrMs Philips van Almonde (1), were under construction. The first one was already launched and commissioned, the latter was not yet in that stage. Two very modern submarines - the O21 and O22 - were under construction too. Both boats were already commissioned and seaworthy, but had not yet finished dive-testing [which is a necessity for submarines to water-tight all gaskets and valves].
(1) These large destroyers with 2,240 tonnes displacement had been desigend in a class of four ships. They were 107 m long with a top speed of 36 knots. Armament would comprise five 12 cm Bofors guns [two twin mounts, one single], four 40 mm Bofors AA guns, four 12,7 mm AA machineguns and eight 53,3 cm torpedo tubes. Additionally 24 mines on a dual rail system, four depth charges mortars and facility for one sea-plane. The armament of the actually launched ships that would later serve in the Royal Navy - under Dutch flag - was altered. The two other ships of this class were commissioned by Rotterdamse Droogdok Maatschappij in Rotterdam. Of those two one was commissioned by the Kriegsmarine and sunk by Allied destroyers on June 9, 1944 as ZH-1.
Preparation to evacuate
Already in the morning of the 10th it was decided that the ships under construction at De Scheld had to be salvaged from the enemy and as such plans were made to tow all four to England. It later became apparent that the HrMs Philips van Almonde was not quite fit to be tugged, but the other three were. The HrMs Philips van Almonde was destroyed in the morning of the 17th by a demo-party [although it would later be salvaged by the Germans].
The HrMs Isaac Sweers was towed [by the tug HrMs Zwarte Zee] from the dock in Flushing to England in the late evening. In the UK the ship would be finished and fitted with new main guns and radar [6 x 10,2 cm guns, 4 x 40 mm Bofors AA, 4 x 2 cm Oerlikon AA, 8 TT 53,3 cm] at Thornycroft Dockyard in Southampton.
Both submarines - which were already self-propelled - were escorted by the auxiliary vessel BV-37 [HrMs Schelde], a tug. It was fitted with a multi-purpose 5 cm gun. The three units safely reached the UK and received a warm welcome.
The Scheld boats in later years
The HrMs Isaac Sweers was commissioned in the Royal Navy later in 1940 and would be sailed by a largely Dutch crew. It participated in a number of sea-battles, of which the most well-known one was the battle at Cape Bon in December 1941. It was present during the unfortunate U-boat sinking of the HrMs Ark Royal in November 1941.
During the battle at Cape Bon [13 December 1941], as a unit in the 4th Destroyer Flotilla under Commander Stokes, the ship contributed to the sinking of two Italian cruisers [6,570 tonnes cruisers Alberico da Barbiano and Amberto di Giussano, the latter being the class first ship]. She was accompanied by the British units HMS Sikh, HMS Legion and HMS Maon. The HrMs Isaac Sweers also damaged the Italian torpedo-boat Cigno during the battle. The fate of the Dutch ship was not very fortunate however. It was sunk by two torpedo hits [U-431] during the Allied landings in North Africa at 13 November 1942 off the coast at Algiers. Out of a crew of 194 only 86 men survived the ordeal.
The O-21 class submarines [O-21 up to and including the O-27] were very modern subs. The O-21 and O-22 even had snort systems that were later adopted by the German U-boats to reload batteries whilst being submerged to periscope depth. The Royal Navy peculiarly enough disapproved of the system and had it removed. The sub's had a max speed of 20/9 knots, a crush depth of 175 metres and four 21" torpedo tubes. A deck-gun of 88 mm had been installed as well as one 4 cm Bofors AA and one 12,7 Vickers AA machinegun. The O-21 u/I O-24 were evacuated to the UK and would sail under the blood-flag of the Royal Navy. The O-25 u/I O-27 were captured and commissioned by the German Kriegsmarine.
The Dutch submarines were concentrated in a small Dutch submarine squadron in the Royal Navy. The modern boats were soon after the Dutch homeland defeat unleashed from British ports and at 30 June 1940 they made their first war patrols - entirely manned by Dutch crews - in the Norwegian waters. The first disaster that struck the modest Dutch submarine fleet in the Royal Navy was felt when the O22 vanished with all hands [42 Dutch, 3 British] during a mission in Norwegian waters in November 1940. Up until today the cause of her sinking is unknown. In 1993 her wreckage was located 70 km offshore the southwestern Norvegian coast and ROV examined. No physical damages were noted. The cause of her loss thus remains a mystery.
The O21 was assigned patrolling duties in the Northsea and the Norvegian waters in the autumn of 1940. Later she was ordered to Gibraltar that would become her new home base. Eventually she ended up in the Mediterranean and managed to sink the German submarine U-95 on 29 November 1941. This event was celebrated through all Allied ranks. It was the first sub-sub sinking of the Allied fleet in the middle of the U-boat terror of the Kriegsmarine. When the few survivors taken on board of the O-21 were disembarked at Gibraltar all Allied ships tributed the O-21.
The O-21 was the Dutch most successful navy unit of the war. It sunk much German, Italian and Japanese tonnage and survived the war. She was decommissioned in 1957. The sister-ships O-23 and O-24 also survived the war, and were decommissioned in 1948 and 1954 respectively.