On 15 June 1940, the last remaining aircraft of the Advanced Air Striking Force returned to Britain. In six weeks almost 200 Battles had been lost, with 99 lost between 10 and 16 May. After the return from France, for a short period of time, the RAF continued to rely on the light bomber. Reforming No. 1 Group and later equipping four new Polish squadrons with the type, it continued to be deployed in operations against shipping massed in the Channel ports for Operation Sealion. Their last combat sortie was mounted on the night of 15/16 October 1940 by No. 301 (Polish) Squadron in a raid on Boulogne, and Nos 12 and 142 Squadrons bombing Calais. Shortly afterwards Battle squadrons of No. 1 Group were re-equipped with Vickers Wellington medium bombers. Battles were operated into 1941 by 88 and 226 Squadrons in Northern Ireland and 98 Squadron in Iceland, for coastal patrol work.