 Although the convoy lost 13 ships, the escorts sank five U-Boats and repulsed the remainder.Occurring in "Black May," the month marking the dramatic decline in the U-Boat effectiveness in WWII, when Allied efforts repulsed or sank most opposition, the Battle with ONS-5 was the final wolfpack attack against the northern merchant trade routes in the Battle of the North Atlantic.As "Manhasset" patrolled near the British merchant ship "Dolius", torpedoed and abandoned earlier in the day but still afloat, she made sound contact with a submarine late in the afternoon.