At 15.28 hours on 29 June 1944, U-984 fired a spread of two LUT torpedoes at convoy ECM-17 about 30 miles south of St. Catherine’s point on the Isle of Wight. The first struck the Edward M. House and the second the H.G. Blasdel. Six minutes later, the U-boat fired a single torpedo at one of the damaged ships and missed but struck the John A. Treutlen. At 15.43 hours, a Gnat was fired which struck the James A. Farrell.

The H.G. Blasdel (Master Roman J. Wank) in station #12 was struck by the torpedo on the port side at the #5 hold. The explosion extensively damaged the interior of the ship. The entire stern section sagged, leaving the after gun platform laying partially submerged. The hold and shaft alley immediately flooded and the engine room filled with water until the top of the cylinders lay submerged. Gasoline in the vehicles in #5 hold caught fire and firefighting parties from the crew extinguished it. The ship was anchored to keep her from drifting into a minefield and to await tugs. None of the eight officers, 36 crewmen and 28 armed guards (the ship was armed with two 3in and eight 20mm guns) were lost, but 76 of the 436 soldiers on board died and 180 others were injured.
At 16.15 hours the wounded were transferred to a British corvette, which came alongside and 15 minutes later a British buoy tender arrived to help with the injured. At 17.00 hours, HMS LST-326 arrived alongside to take off the remaining troops and only a skeleton crew remained on board. Six hours later as the stern threatened to break off, an American tug made fast to the vessel and towed her to Southampton, where the ship was beached bow first. The vessel broke in two and was declared a total loss. The wreck was scrapped in 1947.