Flower-class corvettes like Napanee serving with the Royal Canadian Navy during the Second World War were different from earlier and more traditional sail-driven corvettes. The “corvette” designation was created by the French for classes of small warships; the Royal Navy borrowed the term for a period but discontinued its use in 1877. During the hurried preparations for war in the late 1930s, Winston Churchill reactivated the corvette class, needing a name for smaller ships used in an escort capacity, in this case based on a whaling ship design. The generic name “flower” was used to designate the class of these ships, which – in the Royal Navy – were named after flowering plants.
Corvettes commissioned by the Royal Canadian Navy during the Second World War were named after communities for the most part, to better represent the people who took part in building them. This idea was put forth by Admiral Percy W. Nelles. Sponsors were commonly associated with the community for which the ship was named. Royal Navy corvettes were designed as open sea escorts, while Canadian corvettes were developed for coastal auxiliary roles which was exemplified by their minesweeping gear. Eventually the Canadian corvettes would be modified to allow them to perform better on the open seas.
After a retrofit in 1942, the Napanee was charged with the escort of the damaged HMCS Assiniboine to safety. Later that August, during an escort of convoy ONS-154, the convoy was attacked by U-boats, but managed to repel the attackers and sink submarine U-356.