“She was a class of ship which could be produced quickly and cheaply in the future, to meet the urgent demands of convoy escort.”

By James Brun

THE FLOWER-CLASS corvette may have been a smaller warship, but she was perhaps the most successful escort ever built. 

The more than 250 that were manufactured during World War Two would go on to serve in a dozen Allied navies. Their battlegrounds were the icy waters of the North Atlantic, where they would become the principle maritime weapon protecting the convoys that supplied the United Kingdom and Soviet Union from Hitler’s U-boats. By keeping these shipping lanes open, the Flower-class in turn played a key role in the Allied victory. 

Here are nine important facts about the tiny but mighty Flower-class corvette.

They were designed to be discount escorts

The Flower-class was born of necessity. Following the Munich Crisis of 1938, Britain’s Admiralty was convinced that war with Germany was inevitable. The Royal Navy, understanding that supplies from North America would be vital in any coming struggle, needed a ship that could guard shipping convoys. The British government turned to Middlesbrough shipbuilders, Smith’s Dock Company, to design an inexpensive and easy-to-produce escort ship for immediate emergency production. Meanwhile across the Atlantic, Canada’s small-yet-professional navy also saw the looming threat of war and sought to expand its fleet quickly. Canadian shipbuilders lacked the expertise to build sophisticated warships, so a simple and stout design was required. The corvette emerged as a perfect solution that would meet the needs of both the British and Canadian fleets.

They were inspired by fast sloops from the Age of Sail

The term corvette is derived from the French word for “sloop,” a name suggested by Winston Churchill, who while filling the role of First Lord of the Admiralty remembered such a ship from the days of fighting sail. Originally, vessels in the class were named after types of flowers, such as HMS Gladiolus and HMS Tulip. The corvettes’ odd naming convention also retained an element of British cheekiness: It was thought “that one of Hitler’s sea wolves (U-boats) [having] been destroyed by a vessel named for a flower” would be a public relations victory in Britain and an embarrassment to the Nazis. Conversely, Canadian Flower-class vessels primarily assumed the names of Canadian cities and towns as a means to instill national pride and forge a connection between the population and the country’s relatively young navy. However, there were notable exceptions to this naming convention for Canadian corvettes built in British yards and initially intended for the Royal Navy, such as HMCS Snowberry. 

They were “broad, chunky, and graceless”

The Flower-class was modest but effective. Nicholas Monsarrat described HMS Compass Rose, the fictional corvette in his great work The Cruel Sea, as “two hundred feet long, broad, chunky, and graceless: designed purely for anti-submarine work, and not much more than a floating platform for depth charges, she was the prototype of a class of ship which could be produced quickly and cheaply in the future, to meet the urgent demands of convoy escort.” Monsarrat’s description is both poetic and accurate. The corvette was a mere 205 feet long, 33 feet in the beam, with a 12-foot draft. In general appearance, the Canadian and British corvettes were nearly indistinguishable. The hull was divided into three sections: accommodations were primarily in the forward third of the ship, the midships section contained machinery and engineering spaces, while the aft section contained additional accommodations, storage for provisions, and steering gear. 

The design was based on the whaling vessel Southern Pride, but with modifications to the hull, superstructure, internal layout, and technical equipment. Flower-class corvettes were deliberately simple, allowing for quick production in smaller shipyards such that larger, more experienced shipyards could focus on the manufacture of larger, more advanced warships. Moreover, the simplicity of the corvette allowed for simple and straight-forward operation by the green sailors who would crew them.

The corvette’s machinery was modest. Two Scotch boilers provided steam to a vertically mounted four-cylinder, triple expansion reciprocating engine. The engine would deliver 2,750 horsepower to drive a single shaft-line with a three bladed propeller. The system was rugged, simple-to-operate and easy to maintain.

British corvettes were fitted with a gyrocompass and modern Anti-Submarine detection equipment, commonly referred to as “ASDIC.” Canadian corvettes employed an antiquated magnetic compass that complicated precise navigation, as the primitive direction finding was prone to error if a ship’s own magnetic signature was altered by the heavy North Atlantic seas, or the use of her own guns and depth charges. Operating with a magnetic compass also prevented Canadian corvettes from using modern ASIDC systems, requiring RCN vessels to be fitted with more rudimentary and obsolete submarine detection technology. 

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They lacked heavy guns, but still packed a punch

The Flower-class was lightly armed. She employed a single 102-mm gun positioned on the forecastle, one 40-mm “pom-pom” gun aft, and anti-aircraft machine guns. The Canadian corvettes were also outfitted with a series of .303 Lewis guns and .50 calibre Browning machine guns. The corvette’s most feared weapon, however, was her depth charges, dropped from traps in the stern and thrown by mortars at the waist. In later vessels, the Hedgehog projector was installed to increase the range at which depth charges could be deployed, making the corvette a more formidable adversary against German U-boats.  

Serving on a Flower-class was no pleasure cruise

Life in a corvette was cold and wet. The rounded hulls, a legacy design to the vessels’ whaling roots, caused the ships to ride on top of the seas, rather than dig into the waves like a destroyer’s hull. The design had merits, allowing the relatively small vessel to operate in extreme seas, although the bobbing and corkscrewing motions that resulted took its toll on the ships’ companies. To make matters worse, the vessels were cramped and consistently wet, making comfortable living below decks a difficult affair as water made its way into every compartment of the ship. 

Ships’ companies were small

A corvette’s crew consisted of 90 officers and ratings. Despite the confined quarters, corvettes were the preferred means for rescuing survivors of the torpedoed vessels they escorted due to their manoeuvrability. The “champion survivor-carrier in the entire Allied naval forces” was HMCS Morden, which rescued 357 people between the summer of 1942 and the spring of 1943, from ships torpedoed in the North Atlantic. During one convoy in October of 1942, Morden housed 260 people onboard who had been plucked from the icy sea and transported to safety.

They took the fight to the Wolf Packs

The corvette was a workhorse used to defend ports, sweep for mines, escort convoys, provide limited defence against air attack, and, crucially, hunt and destroy submarines. In fact, the vessel was well suited to this evolving anti-submarine role. She was an excellent sea-keeper, and highly manoeuvrable, able to “turn on a dime, [she was] the only Allied warship with a turning radius tighter than that of a U-boat, and in consequence she was the master of the U-boat in manoeuvring duels that would foil any other surface escort.”

They were among the most plentiful Allied fighting ships of WW2

The Flower-class was the backbone of the Atlantic escort fleet. Initially, the Canadian “government devised a scheme to mass produce corvettes in Canada and trade most of them to the British for Tribal-class destroyers,” a plan that never properly came to fruition. Corvettes were viewed by the government and the navy as the first step in developing an organic Canadian shipbuilding capability that would evolve to provide the RCN with the destroyer fleet it wanted. The initial order by the Canadian government in early 1940 was for 64 corvettes to be built in Canadian shipyards across the country. Orders continued throughout the war to provide the shipyards with ample work. By the war’s end, 269 Flower class corvettes had been built in British and Canadian yards, 123 vessels achieving service in the RCN’s fleet. Although modest in its initial design, evolving wartime technology would modify the class’ design as its role evolved, including the addition of a larger forecastle, new machinery, modified weapons and improved sensors.  

Only one remains

After the war, surplus corvettes were decommissioned, scrapped or transferred to several friendly powers including Chile, the Dominican Republic, Greece and Ireland. Even these were eventually broken up. HMCS Sackville (K181) is the last remaining Allied Flower-class corvette from the Second World War still in existence. She continues to serve as Canada’s Naval Memorial and a National Historic Site. Sackville served as an escort vessel for Atlantic convoys and saw action against U-boats on numerous occasions, including an event in July of 1942 when Sackville attacked three separate U-boats while defending a convoy, seriously damaging two. One year later, Sackville herself was damaged during a devastating wolf pack attack that sank six merchant ships and three escorts, including HMCS St. Croix. Following that engagement, Sackville was removed from active service and converted into a training ship. Each summer the ship is open to visitors at her berth next to the Maritime Museum of the Atlantic, in Halifax, Nova Scotia. 

Although no longer operational, Sackville’s likeness has recently sailed onto the silver screen with a supporting role in the new Tom Hanks film, Greyhound. Scans of the exterior of the ship were used to produce visual effects, bringing the Flower class corvette to life once again, to shepherd her charges across the cruel and unforgiving sea. 

James Brun is an officer in the Royal Canadian Navy. For his daily tweets of rare and fascinating World War Two photos, follow him at @lebrunjames81

Footnotes

1. James B. Lamb, The Corvette Navy: True Stories from Canada’s Atlantic War (Halifax: Nimbus Publishing, 2010). 2.
2. Lamb, The Corvette Navy, 2.
3.  Pierre Berton, Marching as to War: Canada’s Turbulent Years 1899-1953 (Canada: Anchor Canada, 2002), 417.
4.  Marc Milner, “The Humble Corvette: Part 27”, Legion Magazine, June 5, 2008, https://legionmagazine.com/en/2008/06/the-humble-corvette-navy-part-27/. Accessed August 10, 2020.
5.  Nicholas Monsarrat, The Cruel Sea (Toronto: Penguin Books Canada, 2002), 12.
6.  Milner, “The Humble Corvette: Part 27”.
7.  Milner, “The Humble Corvette: Part 27”.
8.  Milner, “The Humble Corvette: Part 27”.
9.  Marc Milner, Canada’s Navy: The First Century (Toronto: University of Toronto Press, 1999), 91.
10.  Milner, Canada’s Navy, 91.
11.  Berton, Marching as to War, 417.
12.  Berton, Marching as to War, 417.
13.  Lamb, The Corvette Navy, 3.
14.  Milner, Canada’s Navy, 82.
15.  Milner, Canada’s Navy, 82.
16.  Milner, Canada’s Navy, 113.
17.  Milner, Canada’s Navy, 133.
18. Canada’s Naval Memorial HMCS Sackville. “The Ship”. Accessed August 10, 2020.  https://hmcssackville.ca/the-ship/.