The Tromp-class was a two-ship series of light cruisers operated by the Royal Netherlands Navy between 1939 and 1969. Officially designated as flotilla leaders, the ships were built to also operate as torpedo and scout cruisers. The two ships, Tromp and Jacob van Heemskerck, were intended to defend the Dutch East Indies against Japan. By the start of World War II, only Tromp was in service: the uncompleted Heemskerck fled to the United Kingdom and was converted into an air-defense cruiser following the Invasion of the Netherlands. The two ships operated with either British or American fleets throughout Asia for the rest of the war, and participated in Allied offensives throughout the Indonesian Archipelago and western Pacific. During the early Cold War, the ships participated in several fleet maneuvers before they were reassigned as training ships and decommissioned in the late 1960s.
Development
During the Interwar period, the Dutch Navy was split between defending the Netherlands and the Dutch East Indies, particularly the island of Java. While the European fleet focused around minelaying, the flotilla in Asia relied on a combination of aircraft, destroyers, and submarines to identify and destroy an invading force near the coastline. Cruisers were vital in this doctrine, as they had the capability to sail out to sea and attack enemy convoys outside the Indonesian archipelago and serve as powerful escorts for allied vessels.
By 1927, the Great Depression had sapped the budget and strength of the Dutch military. Recognizing the need for post-depression rebuilding, the Navy proposed the Vlootplan Deckers (Deckers Fleet Plan) in 1930 to expand the East Indies fleet to a satisfactory size. The plan included two additional light cruisers, described as torpedo cruisers and scout cruisers, intended to operate as flotilla leaders. The two ships were envisioned as a fiscally efficient response to the Japanese Fubuki-class destroyers that outmatched comparable Dutch destroyers. doctrine called for the two ships to be fast enough to lead destroyers in combat while being armed well enough to overpower Japanese cruisers and destroyers.
Their hulls were longitudinally subdivided into 17 torpedo bulkheads between thick that was reinforced by a double hull which extended for about 60% of the ships' length. The main deck was thick and was joined by a lower deck thick above the forward magazine and over the steering gear and aft magazine. The turrets and barbettes were also thick, and the conning tower was protected by of armor.
Jacob van Heemskerck
thumb|Jacob van Heemskerk during World War II, armed as a British air-defense cruiser.When the Netherlands was invaded by Germany, Jacob van Heemskerck was still working up. Her commissioning was hastened, and she fled for Great Britain on the night of 14 May. While her main battery and guns had been installed prior to her departure, the rangefinders for her main battery were still missing. Once arrived in England, she would receive depth charge racks from the torpedo boats G13 and G15. She then escorted members of the Dutch royal family to Canada before she sailed to Portsmouth for completion. As there were no rangefinders available that paired with her armament, and no torpedo tubes had been installed, she would instead be converted into an air-defense cruiser starting in June. Work was finished in February 1941, and she patrolled parts of the North Atlantic before getting deployed to the Pacific with the British East Indies Fleet in 1942. She then participated in the Invasion of Madagascar and patrolled the Indian Ocean, escorting convoys and sinking the German blockade runner Ramses in the process. By 1944, the cruiser returned to Britain and continued to escort convoys in the Mediterranean and Atlantic for the rest of the war. Following German capitulation, she became the first ship to warship to visit Amsterdam after its liberation. After the war, she became the flagship of HNLMS Karel Doormans task force and was reduced to an accommodations ship in 1955.