Allied frigates, sloops, destroyers and hunter-killer groups moved into the paths used by submarines withdrawing toward Norway. Their concentration makes the German failure to question communications security striking. By this account, Allied use of Enigma intelligence had become conspicuous during the final retreat. A less revealing explanation was also available: Norway contained the remaining German-held ports that retreating boats could reach, so Allied forces could anticipate the destination from geography and the course of the war.
Notable Point · 10:51-13:08
How Allied escorts intercepted retreating U-boats
German retreat routes toward Norway became predictable, while decoded communications helped Allied escorts meet the boats on their way.