Following Hitler's December 1941 declaration of war upon the United States German Admiral Karl Doenitz sought to take advantage of the weakly guarded sea-lanes near the American coast and pick off the highly vulnerable, solitary, merchant ships plying these waters. Hitler approved Doenitz's plan, code named Operation Paukenschlag, or drumbeat/roll the drums. Doenitz' U-boats would carry Hitler's war to America and if successful deliver the first blows designed to cripple American shipping and industry.