3. Operation Drumbeat
On December 11, 1941, Italy and Germany declared war on the United States. This has always been considered one of Hitler’s major mistakes.
The German U-boats were a huge success since neither the American civil defense authorities nor the US Navy was sufficiently prepared for submarine defense. Coastal cities, including Manhattan, stayed illuminated, making it simple for german commanders to identify targets. The US Navy (USN) refused to organize coastal shipping into a convoy operation.
After years of intense battle, the US Army Air Force and USN had not developed the cooperative procedures required for fighting submarines. The results were disastrous. Allied maritime losses doubled from the previous year and continued to rise throughout 1942. The British were so concerned by the German successes that they soon dispatched consultants to the US to help develop a coordinated anti-submarine strategy.
This proved to be a smart move: USN would have turned into a very powerful ASW force deploying its own submarines against the Japanese.