With astonishment and respect, the American public in 1916 praised the successful breaking of the British naval blockade by the submarine merchant ship U-Deutschland. It reached the undamaged port of Baltimore and, after being loaded with raw materials important for the war industry, again successfully slipped through the blockade and arrived at its home port. In response, the British Navy placed its naval units in front of US ports with the intention of sending the next German commercial submarine to the bottom. They probably succeeded in this intention with the U-Bremen, which disappeared without a trace. Its fate came true at a time when the German front-line submarine U-53 was already approaching the US coast to attack the siege. What happened here and after is the subject of the following pages.