Late in the First World War, escorts could detach two destroyers after a submarine attack and lay repeated depth-charge patterns around the boat's last known position. Without sonar, the immediate aim was to keep it submerged while the convoy escaped. A boat moving underwater at one or two knots would fall behind merchants steaming at eight to ten knots. A proposed dedicated hunter-killer group could remain longer and wait for the submarine to surface. Escort carriers, destroyer escorts, and improved weapons later made sustained pursuit more effective during the Battle of the Atlantic.
Notable Point · 50:43-52:48
World War I suppression tactics anticipated hunter-killer groups
Destroyers could protect a convoy by holding a submarine underwater until the merchants escaped, even when they could not reliably find and sink it.