The Battle of the Atlantic: Allied Naval Intelligence in World War II


U-1229 Running with Snorkel Mast Extended, August 20, 1944
U.S. Navy photograph in the collections of The Mariners' Museum

A U-boat equipped with a snorkel under attack by U.S. Navy aircraft. Winn and Knowles were deeply concerned when the Germans introduced new submarine technologies such as the snorkel. Moreover, the Germans also began using off-frequency and burst transmitting techniques, making Allied RDF and HF/DF less accurate. Knowles later observed that the Germans might have turned the tide in the Battle of the Atlantic if not for the aggressive use of SIGINT and hunter-killer tactics.