How did corvettes frigates and destroyer escorts protect merchant convoys in World War II?

During World War II, corvettes, frigates, and destroyer escorts were essential for protecting merchant convoys from the threat of German U-boats. These specialized vessels were developed to address the limitations of standard destroyers, which were primarily designed as fast fleet escorts rather than dedicated antisubmarine platforms.123

• Corvettes: The Royal Navy utilized these small, mass-produced vessels for antisubmarine duties in the Atlantic. While they had limited endurance, their primary role was to escort merchant ships and provide a protective screen against submarine attacks.421
• Frigates: Larger than corvettes, these ships were specifically revived by the British to guard convoys. They were typically equipped with sonar (then known as ASDIC) and depth charges to detect and attack submerged submarines.526
• Destroyer Escorts: The U.S. Navy developed these as faster, specialized equivalents to the British frigates. Like their counterparts, they were designed for mass production and were heavily armed with antisubmarine weaponry to secure supply routes.23

These escorts protected convoys by forming a defensive cordon around merchant vessels, using sonar to locate U-boats and depth charges to force them to the surface or destroy them.156