 Its function primarily was to assist a convoy's escort in its defence, though it also had the facility to spend time, which escorts did not have, to continue attacks on U-boats to a successful conclusion rather than having to break off to maintain the guard on the convoy.Walker, however, was determined that the group would be active in destroying U-boats and impressed this aim on his commanders from the outset.The group comprised six sloops of the Black Swan class, making it a highly uniform group, and the sloop design was well suited to the task, with good endurance, adequate speed and specialized anti-submarine armament.