sentences:  The group commenced convoy escort duties in April 1942, in the critical mid-ocean section of the North Atlantic route, operating between Londonderry and St John's Newfoundland.The first convoys, in the spring of 1942, were uneventful and as the pace of the Battle of the Atlantic hotted up in the summer and autumn the group's convoys were escorted without loss.In October 1942, ON 138 came under attack but a vigorous defence by B2 ensured no ships were lost.