As a in the autumn of 1941, Buchheim joined Heinrich Lehmann-Willenbrock and the crew of "U-96" on her seventh patrol in the Battle of the Atlantic. On 27 October 1941, "U-96" left for her seventh patrol and joined group Stoßtrupp three days later. The next day, 31 October, the group made contact with convoy OS 10. "U-96" launched four torpedoes at a long range, one of which struck the Dutch SS "Bennekom". The ship went down half an hour after being hit, taking nine of her crew of 56 with her.