Air cover, provided from ships like this Merchant Aircraft Carrier (MAC) and by land-based aircraft, proved to be one of the decisive factors in winning the battle of the Atlantic.

Aircraft could operate well beyond the range of a convoy's escort ships, attacking submarines or forcing them underwater, where they were less able to keep up with convoys. In addition to purpose-built escort carriers, Merchant Aircraft Carriers (MACs), operated aircraft from flight decks atop modified grain or oil-carrying merchant ships. Three Fairey Swordfish biplanes (centre and right), which were normally armed with depth charges and small rockets, are visible on this MAC.

George Metcalf Archival Collection
CWM 19900279-001_19