1. The story of its strange origin goes back half a century. In the early part of 1918 attacks by German U-boats on our merchant fleet caused the Admiralty so much anxiety that it was decided to take strong, if unorthodox, counter measures and a startling plan was drawn up by "backroom" scientists.

2. During the First World War the Admiralty became alarmed by the many losses of allied merchant shipping to the German U-boats.   In 1916 they evolved a hush-hush plan to erect a series of twelve giant tower constructions across the Straits of Dover (between Dungeness and Cap Gris Nez) as an anti-submarine defence scheme.