With hundreds of merchant ships passing through each week, the Straits of Dover were simultaneously the Allies' artery in the First World War and one of Germany's main naval targets. They were protected by an elaborate system of nets, mines and patrols which was thought to be adequate until during 1917, a series of events surprised and then rocked the Admiralty, the Cabinet and the public.

This article is located in the History of the First World War Volume 6 (REF D522 .H58 1969 V.6).