At 20.05 hours on 24 Jun, 1942, the unarmed John R. Williams (Master Leroy Herbert Allen) struck a mine laid on 11 June by U-373 off Cape May and sank. Four hours earlier the ocean tug had been ordered to proceed to Fenwick Island Shoals to tow a French ship into the Delaware River, but at 18.40 hours the ship was found heading for the river under her own power, so the tug returned to the Cape May Naval Air Station, where she was stationed for rescue and salvage.
The mine struck on the port side just forward of amidships and the explosion sank the vessel instantly. Only the chief engineer, the second assistant and two deckhands survived because they were blown overboard by the explosion. The survivors were picked up after about one hour by YP-334 and taken to Lewes, Delaware and thence to Beebe Memorial Hospital. The remaining four officers and ten crew men were lost.