As the spring of 1942 approached, the British Admiralty had its hands full with the Battle of the Atlantic, which had been raging for two and a half years. U-boat wolf packs, surface raiders, and warplanes had sent about eight million tons of Allied shipping to the bottom, and the situation was getting worse. Slipping out from their havens in the western French ports of Brest, Lorient, La Pallice, Bordeaux, and Saint-Nazaire, the German submarines were now preying on merchant shipping along the U.S. East Coast while continuing to sink Allied vessels at the rate of almost two a day in the North Atlantic.
Brest and Saint-Nazaire were the most heavily fortified German naval bases on the French Atlantic coast. Ringed with mine and torpedo barriers, antiaircraft guns, coastal batteries, and ship patrols, their U-boat pens were bunkers of reinforced concrete several yards thick. But Saint-Nazaire, situated near the mouth of the
Loire River, was much more than a secure refuge for submarines, and its significance haunted the admirals and strategists in Whitehall.
