Convoy coverage and escort shortage

Flower-class corvettes and naval trawlers appeared in both oceanic and coastal escort work, including Mediterranean service at Suda Bay. About 60 percent of early merchant losses came from ships sailing outside convoys, yet the navy could not give every route the same concentration of protection. A convoy off southern or western Africa might face a much lower immediate submarine threat than an Arctic or North Atlantic convoy. During the hunt for Bismarck, Admiral Vian could therefore take the destroyers from a West African convoy and leave it with a C-class anti-aircraft cruiser without losing a merchant ship. The example cautions against treating every wartime convoy as if it experienced the most dangerous moments of the Atlantic campaign.