Norway was invaded by the naval and air forces of Nazi Germany during the early hours of 9 April 1940. The German naval detachment sent to capture Oslo was opposed by Oscarsborg Fortress. The fortress fired at the invaders, sinking the heavy cruiser "Blücher" and damaging the heavy cruiser "Lützow", with heavy German losses that included many of the armed forces, Gestapo agents, and administrative personnel who were to have occupied the Norwegian capital. This led to the withdrawal of the rest of the German flotilla, preventing the invaders' planned dawn occupation of Oslo. The German delay in occupying Oslo, along with swift action by the President of the Storting, C. J. Hambro, created the opportunity for the Norwegian Royal Family, the cabinet, and most of the 150 members of the Storting (parliament) to make a hasty departure from the capital by special train.