The Battle of the Atlantic was waged in order to keep allied shipping lanes open. Around the beginning of July 1940, German U-Boats were attacking merchant ships sailing across the Atlantic in their deadly ‘Wolf Pack' formation. The largest problem the allies had was that all their coastal patrol aircraft were not designed to fly across the ocean which made the merchant ship vulnerable in the mid-Atlantic. This gave the 26 German submarines virtual impunity over the high seas. In 1941, around 2.9 million tonnes of allied cargo destined for England was sent to the ocean floor. In 1942, around 6 million tonnes was sunk.
The solution to this problem came from a coastal patrol ship known as a corvette. These ships were small; the first class ships only being 59 metres in length and the second class or Castle class were 77 metres in length. Designed like whaling ships, they were simple and inexpensive ships to build. Their primary design function was to patrol the Canadian coast. However their versatility made them excellent escorts for the vulnerable merchant ships.
Corvettes were armed with anti- submarine torpedoes, anti-aircraft guns, depth charges to fend off attacks from German U-boats lurking all around them and one 4-inch deck gun. Also, the Corvettes were equipped with listening devices to detect them. The HMCS Lewis was our first naval loss. It was sunk September 19, 1941.
Throughout all of the Battle of the Atlantic, Hitler rarely used his surface ships, relying almost entirely on U-Boats. The German U-Boat attacks peaked with the destruction of 27 merchant vessels. The Battle of the Atlantic never really ended until the end of the war; however as the war dragged on and German resources ran low, the threat of a U-boat attack decreased. In all, 217 merchant vessels were destroyed from the deadly Wolf Pack attack. With the Canadian Corvettes, the seas were secure enough for troops and supplies to be ferried across the Atlantic.