The initial German successes during the winter of 1942-1943 in holding their own against the pressure of Anglo-American forces turned into catastrophe by spring. Aided by Ultra decrypts, Allied air and naval forces first shut down German sea lines of communication between Sicily and North Africa. By April 1943, the Axis partners were reduced to moving supplies and reinforcements across the Mediterranean by air alone. Here again, Ultra revealed their movements, and waiting Allied fighters fought