The film documents the role of the Canadian Merchant Navy and the convoys that brought troops, munitions and supplies to Great Britain during the Battle of the Atlantic in World War II.

Royal Canadian Air Force Supermarine Stranraer seaplanes provide the first aerial protection but once the convoy is out to sea, the RCN destroyers are in charge.

[6] When reading grim battle statistics or as in Atlantic Patrol, narrating a particularly serious topic such as Canadian seaman at war, he was "The Voice of Doom".

[7] The first of the Canada Carries On series, Atlantic Patrol was produced in 35 mm for the theatrical market and was the first short documentary shown in theatres.

[9] The NFB had an arrangement with Famous Players theatres to ensure that Canadians from coast-to-coast could see the documentary series, with further distribution by Columbia Pictures.