USS Constitution is refitted in the late 1930s as a sailing training ship for the US Navy and US Coast Guard Academies and to serve as the Flagship for the CNO. Though primarily a training vessel, she does mount several 3" guns for training of gunnery officers and crew and four M1919 .30 machine guns for self defense.
While at sea on December 7th, 1941, the US enters WWII with the Japanese bombing of Pearl Harbor. Heading back towards Annapolis on the night of 8th, her masthead lookout spots what appears to be a surfaced submarine. Going to battle stations, her Captain wears ship to bring his two port 3" guns to bear. Opening fire, her gun crews score quickly, hitting and comprising her pressure hull. As the German Sailors rush to man their own guns, Constitution opens up with her .30 MGs, sweeping the decks of the submarine.
As Constitution crashes alongside, her men board the Submarine, capturing code materials and an Enigma machine before the U-Boat succumbs to a scuttling charge. Upon her arrival back in Annapolis, Constitution is awarded a Presidential Unit Citation, her Captain recives the Navy Cross and her Gunner the Bronze Star Medal. She is laid up as a receiving ship for the rest of the war.