The weather also played havoc on ships during the Battle of the Atlantic. The winter of 1942-1943 was acclaimed to be the worst in thirty years, and in one month alone eight merchant ships were sunk in gale force seas. The close proximity of vessels in a convoy at night also made collisions at sea an ever-present danger. The first Canadian warship lost in the Second World War was the destroyer HMCS Fraser.

On June 25th, 1940, she was cut in half by the Royal Navy cruiser Calcutta with the loss of 47 lives when she crossed the cruiser's bow. Ironically, HMCS Margaree, the destroyer commissioned to replace the Fraser, met a similar fate when she was lost in a collision with the freighter Port Fairy. Over 140 of her ship's company was lost including many survivors from HMCS Fraser.