England needed food. The Allies needed troops and war materiel to press their campaigns in Italy and North Africa. American shipyards were churning out Liberty ships—low-cost cargo ships that were being mass-produced in unheard-of numbers—but the U-boats in 1942 were able to sink ships faster than America could make them. Making things worse was the fact that the Germans were reading the cipher the Allies used to direct their convoys, something the Americans suspected but the British were slow to admit.
