Counter-measures Get Under Way
The decision to implement convoys and blackout coastal towns to make ships more difficult to see came slowly. The situation began to change in April when Andrews implemented a limited convoy system in which ships traveled only during daylight hours. Full convoys were in operation by mid-May, resulting in an immediate reduction of Allied shipping losses off the East Coast as Dönitz withdrew the U-boats to seek easier pickings elsewhere. The convoy system was later extended to the Gulf of Mexico with similar dramatic effects, thus proving that Andrews' initial rejection of the convoy system was wrong.
In March, 24 Royal Navy anti-submarine trawlers and 10 corvettes were transferred from the UK for the defence of the U.S. East Coast. That same month the Royal Canadian Navy began escorting convoys between Boston and Halifax. The British also transferred 53 Squadron, RAF Coastal Command to Quonset Point, Rhode Island to protect New York Harbor during July 1942. This squadron moved to Trinidad in August, with a U.S. squadron, to protect the critical sea lanes from the Venezuelan oil fields and then back to Norfolk, Virginia until the end of 1942. Royal Navy and Royal Canadian Navy ships took over escort duties in the Caribbean and on the Aruba–New York tanker run. Fast CU convoys were organized to maintain petroleum fuel stockpiles on the British Isles.
The Kriegsmarine, while enormously effective during this period, did not go without losses. Sinkings of German U-boats at the hands of United States forces during this time included:
- U-85: sunk 14 April by the destroyer USS Roper in position 35°55′01″N 75°13′01″W / 35.917°N 75.217°W / 35.917; -75.217 off Cape Hatteras, first sinking in U.S. waters
- U-352: sunk 9 May by the cutter Icarus in position 34°12′00″N 76°34′59″W / 34.2°N 76.583°W / 34.2; -76.583 off Cape Hatteras
- U-157: sunk 13 June by the cutter Thetis in position 24°13′01″N 82°03′00″W / 24.217°N 82.05°W / 24.217; -82.05 off Havana, Cuba
- U-158: sunk 30 June by Mariner aircraft (USN VP-74) in position 32°49′59″N 67°28′01″W / 32.833°N 67.467°W / 32.833; -67.467 west of Bermuda
- U-215: sunk 3 July by the Armed ASW Trawler HMS Le Tiger in position 41°29′N 66°23′W / 41.48°N 66.38°W / 41.48; -66.38 by depth charges
- U-701: sunk 7 July by Lockheed Hudson aircraft in position 34°49′59″N 74°55′01″W / 34.833°N 74.917°W / 34.833; -74.917 off Cape Hatteras
- U-153: sunk 13 July by the destroyer USS Lansdowne in position 9°55′59″N 81°28′59″W / 9.933°N 81.483°W / 9.933; -81.483 off Colón, Panama
- U-576: sunk 15 July by two Kingfisher aircraft and ramming by the U.S. motor vessel Unicoi in position 34°51′00″N 75°22′01″W / 34.85°N 75.367°W / 34.85; -75.367 off Cape Hatteras
- U-166: sunk 30 July by the US Navy patrol craft, PC 566, in position 28°31′01″N 90°45′00″W / 28.517°N 90.75°W / 28.517; -90.75 in the Gulf of Mexico, the only U-boat sunk in the Gulf of Mexico during World War II
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