ABSTRACT
The invasion of England depended on security at sea and domination in the air. The command of the sea was not the responsibility of the German Navy alone, for the crossing was to take place largely in the Straits of Dover, a narrow waterway easily covered by heavy artillery on shore. Great emphasis was put on the protection of the flanks of the invasion fleet by mine barriers but the conditions of the Channel made it difficult to create such defences effectively. Additional mines were laid by the Luftwaffe to cut Portsmouth off from the open sea and inshore mines were laid by German motor torpedo boats. On and under the sea the German Navy added to the Royal Navy's problems in resisting invasion, in part because of the forces they could deploy and in yet greater part because of what the British thought they could do.
