In February 1938 the Australian Commonwealth Naval Board (ACNB), which consisted of both government officials and flag officers of the Australian navy, defined that there was an urgent requirement for several dozens of military vessels for local defense and guard duties. The ships would have to be built both cheap and simple so there was a need for a simple and basic design. The basic requirements were defined by a displacement of approximately 500 tons, a speed of approximately 10 knots and a range of 2,000 nautical miles. The vessels would be used for mine detection and for submarine hunting. Soon it became clear that the basic requirements, as proposed by the ACNB, would not completely comply.
One of the major shortcomings of the German Luftwaffe during the Second World War was the almost total lack of long-range heavy bombers. Not long after the Germans had begun their assault on Great-Britain, they found themselves in need of a heavy bomber suitable for attacking the British convoys far out in the Atlantic Ocean. Since the need was urgent and the time to develop a new aircraft was too short, there was only one option open to them, converting the new airliner designed by Kurt Tank, the Focke Wulf Fw 200 Condor, to a bomber. Strangely, this became one of the most succesful conversions of the war, although the Condor was not ideally suited for this role. The success lay in the fact that British convoys were extremely vulnerable to and inadequately protected from aerial attacks.
September 24th 1941, the Dutch navy contacted the British Admiralty with the request to take over three new British T-class submarines. The Royal Dutch Navy had lost Hr. Ms. O 8 and Hr. Ms. O 12, due to the fact that they fell into the hands of the Germans on the14th of May 1940. Furthermore the navy would like Hr. Ms. K VII and the three boats of the K VIII-class to be removed from the fleet and in order to provide the available crew the opportunity to perform their war tasks, new submarines were required. At that time, the Royal Navy could not do without the T-class submarines, but did offer two smaller, but modern, U-class submarines to the Dutch navy.
On his own initiative Fokker built a, for those days, very modern looking aircraft in 1936. The twin boom tail, the short fuselage and the two engines were characteristic. Though it was intended to be a fighter aircraft, the machine got the type casting of "fighter cruiser" in order to express the extra characteristics compared to a fighter. It was a true cruiser. Even when the aircraft had not yet made its maiden flight, it was the focus of the attention at the Paris Air Show of 1936 because of its appearance and heavy armament (two 23 mm Madsen guns and two 7.9 mm machine guns in the nose cone and a flexible 7.9 mm machine gun in the rear of the fuselage).