During the First World War, after the German Navy had declared unrestricted naval warfare, the British Admiralty introduced the convoy system in May 1917 to protect merchant shipping.
Between May and December of 1917, Allied shipping losses declined by more than half, demonstrating that the convoy system worked. With the outbreak of the Second World War in 1939, the British immediately adopted the convoy system once again, knowing it was vital for continuing the war effort. However, after the United States entered the war in December 1941, they decided not to rely on convoys reasoning that individual ships had a better chance on their own.
As a result, they lost over 600 merchant ships to U-boats during the next six months, with many of them sunk within sight of US coastal cities. It was only after the Americans belatedly introduced the convoy system in May 1942 that Allied shipping losses dramatically declined.
The Convoy System - First World War
Throughout both World Wars, the backbone of the Allied war effort was the convoy system. These groups of merchant ships, shepherded across the Atlantic convoy lanes by a handful of corvettes and destroyers, supplied much of the food, fuel, ammunition and material necessary to keep modern armies functioning. Attacked at every turn by German U-boats and surface raiders, often taking horrific losses, the convoys allowed the Allied to harness the industrial and agricultural productivity of the Americas.
The process of convoying merchant ships dates back to the 17th century. The Dutch merchantmen traveling to the Baltic or the East-Indies often traveled in groups or with an escort for greater protection against either pirates, or during times of war, the warships of hostile powers. This system was widely used by every naval power throughout the eighteenth and nineteenth century and proved a natural defence against the deprivations of predatory raiders.
It was largely abandoned during the First World War however; as it was believed that individual ships traveling at their maximum speed would be safer than a larger grouping, traveling only as fast as the weakest ship in the pack. However, the primary Atlantic predator was no longer the surface raider; the German development of the Unterseeboot (Under-Sea Boat) or U-Boat, had made solitary merchant vessels highly vulnerable.
As the number of U-boats increased, Allied and neutral shipping losses continued to climb. By June 1916 the Allies were losing 37,000 tons of shipping per month. In December the number had risen to 80,000 tons. In February 1917, in a last ditch effort to win the war, German declared unrestricted submarine warfare around the British Isles. Shipping losses soon climbed to 300,000 tones per month, then to half a million by June 1917.
The strategy of starving Britain into submission seemed to be working, in April the First Sea Lord, Sir John Jellico stated: "It is my firm conviction that we shall lose the war by the starvation of this country." It was the convoy system which saved Great Britain from defeat. Instituted in May 1917, British losses fell off sharply while German U-Boat losses increased.
Early U-boats preferred to surface and sink their targets with their deck gun rather than use torpedoes, which were expensive and far less accurate. Once merchant ships began grouping together with warship escorts, this tactic became suicide, forcing the German boats to rely increasingly upon less effective hit and run torpedo raids.
The Convoy System - Second World War
The lessons of the First World War were taken to heart by the British admiralty. At the outbreak of hostilities in September 1939, a convoy system was immediately instituted to begin shipping goods from Canada to Great Britain. Convoy HX-1, the first convoy of the war, sailed safely from Halifax to Liverpool under the escort of both Canadian and British warships on 16 September 1939. Soon, two convoys a week were sailing from Halifax.
The German strategy was the same as it had been in the First World War: to sink enough shipping to force Great Britain out of the war. Yet the tactics were different. Rather than operating independently, the U-Boats of the Second World War normally operated in 'Wolf Packs.' This was a tactic devised by German Admiral Karl Dönitz, which called for one boat to radio the location of a convoy to a larger group, which would then converge in a mass attack, thus overwhelming the escort and inflicting maximum damage.
As German resources increased, the Wolf Packs took an increasingly severe toll on Allied shipping. The Canadian Navy was not large enough to provide an effective escort for the rapidly increasing number of vessels needing it and, with the British navy heavily tasked in the North Sea, Pacific and Mediterranean, the merchant marine was forced to settle with very light escorts.
As German submarine strength steadily increased and the Kriegsmarine moved its operations west, Canadian responsibilities only increased. On 31 May 1941, Commodore Leonard Murray of the RCN was appointed commander of the Newfoundland Escort Force. By July, this force totalled 12 groups of Canadian and British warships, with the responsibility for escorting convoys as far out as the mid-Atlantic.
With the American entry into the war after Pearl Harbour, the U-Boats shifted their focus south to the shipping along the Eastern American Seaboard. With many of America's frigates and destroyers sent to the Pacific, the RCN's responsibility expanded further to include guarding American ships traveling to British ports.
Initially, the United States avoided the used of convoys and the result was massive shipping losses in what the U-Boat captains called a 'happy time.' From January to July 1942, nearly 400 ships were sunk for the loss of only seven U-boats. Through the spring of 1942, the US Navy gradually built up a convoy system, but still remained dependent on Canadian assistance.
By late 1942 the RCN, which had begun the war with only 6 destroyers, had 16,000 members serving in 188 warships. With this expanded fleet, it was largely responsible for what was called the triangle run: escorting much of the transatlantic shipping from New York and Boston to Halifax and thence to the mid Atlantic, where escort duty was taken over by the British.
By 1943 the convoy battles had reached their climax; in March, 108 Allied ships – 569,000 tonnes of vital shipping – was destroyed. However by that point the fortunes of war were beginning to tip. New warships and technologies, along with longer range aircraft patrolling deep into the Atlantic began to sink German submarines in dramatically increasing numbers. Between April and July 1943, 109 U-boat were lost and Admiral Dönitz withdrew his boats from the Atlantic to lick their wounds. German submarines would return and continue the Battle of the Atlantic until the end of the war, however they would never again regain the strength needed to starve Britain into submission.
During the war there were over 25,000 merchant passages made from North American to British ports under the escort of Canadian warships. These vessels delivered approximately 165 million tonnes of cargo to feed the British people, supply the Allied armies and fuel the war effort. Nearly 1,600 Canadians and Newfoundlanders served to bring these vital supplies across the ocean, risking their lives against not only U-Boats but the dangers posed by the elements and the sea.
Whereas in 1939 the Canadian merchant marine and ship building industry were relatively small, over the course of the war Canada built the world's fourth largest merchant fleet guarded by the third largest navy. The number of ships that poured from Canadian shipyards during the war was extraordinary. In fact it was described by an official of the British Ministry of War Transport as "remarkable, astonishing and magnificent." From the first delivery in December 1941 to shortly after the war ended in 1945, Canada produced over 380 cargo ships, 280 escort ships (destroyers, corvettes, and frigates), over 200 minesweepers, 250 tugs and 3,300 landing craft.
In September 1942 as the U-Boats were increasing their attacks, Winston Churchill declared that, "without ships, we cannot live." The convoys were the life-blood that sustained not only the war effort but the survival of the British people themselves. Without the dedication of the merchant convoys and their naval escorts, the massive material superiority which the Allies used to such advantage against the Germans could never have been amassed, the enormous Allied Armies could not have been fed and Britain, starved and alone in Europe would have had no choice but to have sued for peace.