The unarmed Collamer (Master John M. Hultman) had lost convoy HX-178 in heavy seas, unable to maintain convoy speed and with damage to her deck cargo, the master decided to return to Halifax.

At 11.35 hours on 5 March 1942 the Collamer was hit by one torpedo from U-404 off the coast of Nova Scotia, while proceeding on a nonevasive course in rough seas at 9 knots. The torpedo struck the starboard side amidships, causing the boilers to explode and killed the engine room crew of three officers and four men. The ship began to sink fast by the stern and the crew of seven officers and 31 men abandoned ship in two lifeboats. But before they could get away, a second torpedo struck the ship underneath the bridge just aft of the #2 hatch on the port side. A terrific explosion caused the ship to sink immediately by the stern. The radio operator had managed to send a SOS to Halifax. After several hours, two aircraft appeared and signaled the British steam merchant Empire Woodcock, which picked up the survivors.