Hunter-killer Groups, also known as Convoy Support Groups, were groupings of anti-submarine warships that were actively deployed to attack German U-boats in the Battle of the Atlantic during World War II.
The groups origins lay in 1942 when the British formed groups that could reinforce the Escort Group accompanying a trans-atlantic convoy. The Allied Atlantic Convoy Conference of early 1943 agreed to set up ten groups of anti-submarine warships with an escort carrier in each. Five Anglo-Canadian groups would operate in the North Atlantic ocean and five US groups in the Middle Atlantic. The advances in signals intelligence such as 'Huff-Duff' (HF/DF), in cryptological intelligence such as Ultra, and in detection technologies such as radar and sonar/ASDIC enabled the Allied navies to form flotillas designed actively to hunt down submarines and sink them. A hunter-killer group would typically be formed around an escort carrier to provide aerial reconnaissance and air cover, with a number of corvettes, destroyers, destroyer escorts, frigates, and/or United States Coast Guard Cutters armed with depth charges and Hedgehog anti-submarine mortar.