 British efforts were helped by a gradual increase in the number of escort vessels available as the old ex-American destroyers and the new British- and Canadian-built s were now coming into service in numbers.Many of these ships became part of the huge expansion of the Royal Canadian Navy, which grew from a handful of destroyers at the outbreak of war to take an increasing share of convoy escort duty.Others of the new ships were manned by Free French, Norwegian and Dutch crews, but these were a tiny minority of the total number, and directly under British command.