Extraordinary story from WWII. Messerschmitt decides not to shoot down B17

An American B-17 stationed in England was severely damaged by German flak and the crew was wounded and one dead during a bombing raid over Bremen, northern Germany.
As the plane struggles to limp back to England, a Messerschmitt approaches to finish off the crippled B-17 but surprisingly, the German pilot does not shoot and instead escorts the B-17 to the safety of international water.