The crack ASW group behind convoy escorts

Routine convoy escorts included Flower-class corvettes, Hunt-class escort destroyers, and older V and W destroyers. A convoy facing concentrated submarine attacks needed a mobile group that could reinforce those escorts. Black Swan groups supplied specialist anti-submarine crews and commanders, with Johnnie Walker the best-known example. Their expected arrival could give hard-pressed escorts confidence that they only needed to hold on until help reached them. The elite reputation also shaped the sloop crews' own expectations of their performance. This morale argument does not depend on proving that every opposing submarine commander shared that reputation.