U-48

Following the signing of the Treaty of Versailles in 1919, Germany was not permitted to build or operate submarines. However clandestine training onboard Finnish and Spanish submarines took place and U-boats were still built to German designs in Dutch yards.

At the outset of the Second World War, Dönitz argued for a 300-strong U-boat fleet, since his force of 57 U-boats ‘could only inflict pin-p...