During the Second World War, Canada contributed a sizable fleet of naval vessels to help in convoy escort and anti-submarine warfare during the Battle of the North Atlantic.
These were the British Corvette class warships. As the need for the convoy system became urgent early in the war, Canada offered the services of its smaller boat yards, eventually building over 100 of these vessels.
These small, maneuverable but lightly armed warships played an invaluable role in convoy escort. Their role in anti-submarine warfare became more important later in the war as detection systems improved. The Corvettes that served in the Royal Canadian Navy were all named after Canadian towns and cities, such as the HMCS Calgary.
The Corvette Story
Originally based on the design of a whaling boat, the corvette was a small, simple auxiliary vessel with few crew comforts. Built by necessity, the corvette was mass produced to serve the role of patrol vessel and convoy escort. Lightly armed and often poorly equipped, these small vessels struggled throughout the war to keep Canadian waters and the Atlantic convoy lanes safe from attack.
Yet, as German U-boat raids on merchant shipping increased, and Allied naval reserves became stretched to their limits, the corvette crews often found themselves the only thing standing between the U-Boats and the convoy lifeline to Britain.
The Second World War
In September 1939, the Royal Canadian Navy boasted a total fleet personnel strength of almost 3,700 hands, including reservists. The fleet consisted of six fairly modern destroyers, and only four minesweepers. Yet, by 1945 the navy had grown to 400 ships with a strength of 95,750 officers and men. This extraordinary expansion was not a simple task. Canada did not have the naval training infrastructure to absorb the masses of new recruits, Canadian shipyards were unaccustomed to naval production and Canadian industry unable to produce much of the equipment for large warships.
The result was the construction of the flower class corvette, a design which would be improved and upgraded throughout the war. Based on a British design for a whaling vessel, the corvette was a simple auxiliary ship that Canadian shipyards could turn out en mass and hastily trained Canadian sailors could man with relative ease. From 1939 to 1940 alone, Canada built 70 such ships, each taking roughly 10 months and roughly $600,000 to complete.
The flower class was so named because the British ships of this design were all named after a flower. Naval historian Ken Macpherson observed that it was nice to boast publicly that a deadly U-Boat had been destroyed by the likes of HMS Buttercup, something only the British would think to do.
The Canadian vessels were soon renamed "Town class" after the many Canadian communities who lent them their names. The differences between the British and Canadian corvettes were small but important. Hindered by a more primitive industrial base in 1939, Canadian vessels were lightly armed, carrying only a .50 calibre machine gun and depth charge launchers. The Town class vessels also lacked the gyro compasses of their British counterparts.
The Canadian magnetic compasses, useful for merchant ships, were decidedly unsuitable for use on a warship. Foul weather and the shock of depth charges often threw these compasses askew and hindered both navigation and depth charge range calculations.
The corvette was highly manoeuvrable however. It could turn a complete circle in 100 seconds and easily outmanoeuvre a surfaced U-Boat. When a corvette acquired a U-Boat on its primitive sonar, it could drop depth charge loaded with 300 pounds of TNT. Unlike conventional bombs, these charges were not meant to destroy the enemy with a direct impact but rather to force an enemy submarine to the surface by crushing its pressure hull with a shock wave.
Once on the surface, a corvette had a machine gun and a First World War deck gun. These weapons were highly inaccurate in a choppy sea and often a corvette captain would simply forego their use and resort to the oldest weapon in naval warfare – the ram. Such an attack often seriously damaged the corvette, yet it was a simple and effective way to kill a U-Boat before it could use its superior speed to escape.
Killing an enemy submarine was, however, a rare occasion. A skilled U-Boat captain usually had little to fear from the lightly armed vessels. During the war only 14 German submarines were destroyed by Canadian corvettes, with the majority coming in 1943 and 1944. The primary task of the corvette was not to hunt enemy boats, but to protect Allied shipping.
As German attacks escalated from 1940 to 1943 the demand for escort vessels became increasingly desperate. With the British Navy overstretched and committed to theatres around the world, the job of securing the Atlantic convoy lanes fell heavily on the Canadians.
By May 1941 the British had requested that the Canadian Navy take over responsibility for the western convoy approaches. Commodore Leonard Murray was placed in command of the newly created Newfoundland Escort Force, giving Canada its first theatre command.
Escorting merchant convoys across the Atlantic was strenuous and exhausting work. Canadian escort groups shepherded convoys from Canada, and later the United States and the Caribbean, across the Atlantic Ocean. The Newfoundland to Derry run took roughly 14 days and as Newfoundland was not yet part of Canada, the crews of the Canadian corvettes rarely had the opportunity to receive shore leave at home.
Corvettes were damp, crowded and uncomfortable vessels under even the best circumstances. Small and light, they were unstable vessels; battered by waves in even a calm sea, sailors joked that corvettes would roll on wet grass. Water was a part of life onboard and once the crew was wet, they normally stayed wet for the remainder of the voyage. There was no bathing onboard and the cramped compartments soon became foul.
As the vessels were upgraded throughout the war, the already cramped living conditions worsened. By 1941 the ships’ complement swelled from 50 to about 100 as the vessels were slowly modernized. Modernization was a painful procedure for the Canadian corvettes. Better navigational equipment, radar, sonar and weapons were difficult to manufacture in Canada.
The structural upgrades needed to make the ships more seaworthy were also extremely time-consuming. And, as the Atlantic convoys were suffering increasing losses throughout 1941 – 1942 it was feared that modernization would have taken ships out of service for months during which they were desperately needed.
Yet as shipping losses mounted, improvements to the escort fleet became unavoidable. By 1942 primitive radar was being mounted on some vessels and by 1943 modernization was slowly moving forward in a number of Canada’s growing shipyards. By 1944 the Canadian fleet had been upgraded to include the superior type 271 surface radar to locate surfaced submarines and the new Hedgehog anti-submarine weapon system.
The Hedgehog was a series of 24 small mortar-style bombs launched simultaneously at a section of ocean suspected of harbouring a submarine. Blanketing an area of 120 x 140 feet, these bombs exploded on contact and often only one small detonation was enough to rupture a submarine’s pressure hull and force it to the surface. While the success rate of depth charge attacks was roughly 6 %, the hedgehog had reached an impressive 30% by 1944.
By May of 1944 as the British Navy had largely withdrawn from the Atlantic to prepare for the D-Day invasions, leaving the Canadian fleet responsible for guarding the convoy lanes all the way from Canada to Great Britain.
A handful of the Canadian corvettes were even tasked to assist in the landings, both in France and in the Mediterranean. There were 19 Canadian corvettes supporting Operation Overlord in Normandy, while the Canadian ships supporting the Torch landings in Africa claimed an impressive five German U-Boat kills.
By the close of hostilities, the Canadian Navy had 114 corvettes still in service, with 10 having been lost to enemy action. These vessels, while far from the most impressive of Allied warships, provided a vital service under some of the most difficult conditions.
Always fighting at a disadvantage in what was essentially an underpowered whaling vessel, the Canadian corvette fleet nevertheless helped to secure the Allied supply lines when there were no other vessels capable of doing the job. The Corvette story adapted from the book, Corvettes of the Royal Canadian Navy, 1939-1945 by Ken Macpherson.