Chambly escorted trade convoys between Halifax Harbour and the Western Approaches through the battle of the Atlantic and, together with HMCS Moose Jaw, achieved the RCN's first U-boat kill of the war.

[3][4][5] The "corvette" designation was created by the French as a class of small warships; the Royal Navy borrowed the term for a period but discontinued its use in 1877.

[9] Chambly was one of the first three Royal Canadian Navy corvettes available for Atlantic service when the St. Lawrence River froze in late 1940.

In May 1941 she took part in the Canadian Navy's secret trials of diffused lighting camouflage, a technology for concealing ships from submarines at night.

She was able to give steering instructions that found the submarine dead ahead when the traditional plotters were convinced it was 28 degrees to one side.

With Support Group 9, she narrowly avoided destruction when an acoustic torpedo exploded in the propeller wash of her wake during the battle for convoys ONS 18/ON 202.