By 1945 the Royal Navy could combine convoy escort with offensive hunter groups instead of merely reacting around threatened shipping. Carrier-borne Swordfish could patrol at night with radar, searchlights, rockets, or depth charges and were fast enough to overtake any submerged boat. Their radar might detect a periscope or snorkel, making darkness less reliable as cover for a submarine trying to enter a convoy. Improved ASDIC, long-range land-based aircraft, signals and human intelligence, and far more numerous escorts completed the layered system. Late Type XXI-style submarines would therefore have faced a mature network rather than the thin defenses of 1940, making simple performance comparisons misleading.
Chapter · 23:19-27:02
Escort carriers anchor the Royal Navy's late-war ASW system
By 1945, escort-carrier aircraft, radar, improved ASDIC, intelligence, land-based patrols, and numerous escorts formed a layered system against advanced U-boats.