The River-class frigates were developed in the early 1940s on the same premise as the preceding Flower-class corvettes; quick and cheap to build convoy escort vessels which would protect merchant shipping in the North Atlantic from the ever growing axis submarine threat. Unlike the Flower-class corvettes however, River-class frigates were larger, had a longer range and were overall more suitable for operations in the North Atlantic.
Production of the River-class frigates began in 1941, with the first vessels being completed in the following year. Overall, over 150 River-class frigates would be built throughout WW2, of which only 17 were lost in combat actions.
River-class frigates primarily served with the Royal Navy, but they also served with many other nations during WW2, such as Canada, Australia, the USA, France, Netherlands and South Africa. They remained popular even after the war, serving with Denmark, Norway, New Zealand, India, Portugal, Egypt, Argentina, Chile and many more nations! The last River-class frigates were decommissioned from military service during the 1970s.