The barrage attack was developed during the Battle of the Atlantic in World War II as an anti-submarine measure.
The design of submarines, to resist the enormous pressure of the water at depth, made them also resistant to the effects of underwater explosions; a depth charge of the Second World War had to explode within about 26 feet of its target to have any serious effect.
The barrage was expensive in terms of resources and could quickly empty an escort's magazine, so it could only be used in stubborn cases.
The practice of equipping convoy ships with reserves of depth charges to re-arm escorts when necessary went some way to alleviate this problem.
The advent of more effective weapons such as Hedgehog, Squid, and the Mk X depth charge also made the barrage less necessary.