"Reichsmarschall" Hermann Göring, Commander-in-Chief of the "Luftwaffe", believed the invasion could not succeed and doubted whether the German air force would be able to win unchallenged control of the skies; nevertheless he hoped that an early victory in the Battle of Britain would force the UK government to negotiate, without any need for an invasion. Adolf Galland, commander of fighters at the time, claimed invasion plans were not serious and that there was a palpable sense of relief in the when it was finally called off. "Generalfeldmarschall" Gerd von Rundstedt also took this view and thought that Hitler never seriously intended to invade Britain; he was convinced that the whole thing was a bluff to put pressure on the British government to come to terms following the Fall of France. He observed that Napoleon had failed to invade and the difficulties that confounded him did not appear to have been solved by the Sea Lion planners. In fact, in November 1939, the German naval staff produced a study on the possibility of an invasion of Britain and concluded that it required two preconditions, air and naval superiority, neither of which Germany ever had. Grand Admiral Karl Dönitz believed air superiority was not enough and admitted, "We possessed neither control of the air or the sea; nor were we in any position to gain it." Grand Admiral Erich Raeder thought it would be impossible for Germany to attempt an invasion until the spring of 1941; he instead called for Malta and the Suez Canal to be overrun so German forces could link up with Japanese forces in the Indian Ocean to bring about the collapse of the British Empire in the Far East, and prevent the Americans from being able to use British bases if the United States entered the war.