The Royal Canadian Navy, which had only 13 warships and 3,000 men in 1939, grew in size and responsibility during the war. By the end of the conflict, Canada's navy possessed 365 warships and 100,000 men. The RCN served in a variety of capacities during the war. For example, 110 Canadian ships participated in the D-Day offensive in 1944. The RCN also played a crucial role in escorting convoys of merchant vessels through the treacherous North Atlantic. Indeed, in 1943, the RCN was assigned its own sector to patrol.
These duties were vital to the success of the struggle against Hitler. The supply of food, arms, and other supplies from North America was a critical lifeline for Britain and the entire Allied war effort. Germany invested tremendous energy in attempting to destroy merchant fleets in the North Atlantic. The convoy system offered some protection, but sea duty was still enormously perilous. German U-boats (submarines) were the danger. On 16 April 1945, the minesweeper Esquimalt went missing and 44 of the 70-man crew were lost. Death came quickly in the frigid North Atlantic, and rescue was often extremely difficult.
The U-boat war was a constant and deadly game of one-upmanship for both sides. The Germans introduced U-boats at the beginning of the war, but, for the first two and a half years, their relatively limited range and armaments meant they were only a threat to merchant ships travelling alone in the North Atlantic. Gradually the Germans improved U-boat technology, giving them greater range and destructive power. They also developed the wolfpack, a system in which groups of German submarines hunted together. By May of 1942, German submarines were operating directly in Canadian coastal waters, including in the St. Lawrence River itself. In response, the Allies improved the planning and deployment of the convoy system, increased naval resources to include escort carriers and anti-submarine vessels like the corvettes, improved radar and sonar detection, and extended support from the air further and further into the North Atlantic. The Germans, in turn, improved the ability of the U-boats to remain submerged and to detect Allied radar. Although the U-boats were not as great a threat in the last year of the war, they remained a potent weapon in the German arsenal. Ominously, Germany had newer and still more deadly models under construction when the war ended.
The seamen who manned the merchant vessels faced similar risks. The percentage of deaths in the Canadian merchant marine was high: thirteen per cent of merchant seamen lost their lives in the war. Less than half of merchant ship crewmen survived the sinking of their ships.
After the Allied command assigned the RCN the task of escorting convoys in the mid-Atlantic run in 1941, RCN warships provided protection for numerous merchant vessels bound for Great Britain. While the warships lurched at the speed of the slowest merchant ship, the sailors, ever alert to the menace of U-boat attacks, nervously went about their normal duties. In the bitterly cold winter months they chipped away the thick sheets of ice that built up on the decks, equipment, and bulkheads. Ice could form most of the year in the North Atlantic. It had to be removed because if it accumulated, it could cause the ship to capsize.
German wolf packs posed a much greater threat than ice, as the experience of convoy SC 107 attests. The convoy had fewer escorts than usual, as RCN corvettes and destroyers had been assigned to protect the Anglo-American fleet during "Operation Torch," the invasion of North Africa. U-boat scouts spotted SC 107 near Newfoundland as it was about to enter the mid-Atlantic run. As night fell, a wolf pack of 17 U-boats swarmed the convoy. Snowflake rockets lit up the night sky, while merchant ships desperately tried to fend off the onslaught. Although the outnumbered escorts helped ward off some of the submarines, three managed to get through, and they sank eight ships. One of the ships, an ammunition transport, exploded with such fury that sailors aboard ships miles away thought that they themselves had been torpedoed. The carnage continued the following night when two more U-boats entered the protective inner circle of SC 107 and sank several more ships. On the fifth day of the battle, reinforcements for the beleaguered convoy finally arrived in the form of escorts and long-range Liberator bombers. The wolf pack broke off the attack, but not before it had inflicted heavy losses: SC 107 lost 15 ships out of a total of 42. The German navy lost but one submarine.