Operation Artichoke

This was an Allied anti-submarine tactic (1942/45).

In the event that a merchant vessel was torpedoed in the middle of a convoy, on the issue of the executive order by the commander of the escort, the escort warship immediately astern of the torpedoed vessel moved at maximum sonar speed to the position of the torpedoed vessel, in the process searching for any sign of the attacking U-boat. At the same time the escort warships ahead of the convoy reversed course and made, at maximum sonar speed, through the columns of merchant vessels to reach a position 1 mile (1.6 km) astern of the convoy’s position at the time of the original torpedo attack, then reversed course once more and followed the convoy at the warships' optimum sonar search speed in the hope of detecting the attacking U-boat, now submerged, as it sought to escape or reload its tubes for another attack.