Convoys

Britain depended on vital supplies of food, equipment and raw materials from overseas, notably from North America and the Empire. These goods were transported in thousands of merchant ships, which were vulnerable to attack by German submarines (U-boats). As there were not enough warships to protect thousands of individual merchant ships, they were grouped into convoys with naval escorts, making them hard to find and difficult to attack.

Merchant shipping was placed under Admiralty control on 26 August 1939, and the first convoy sailed on 2 September. Four days later, the first regular series of convoys began. Convoy FS1 – standing for Forth-Southbound – was tasked with protecting the coal supply routes along Britain’s east coast.

Following the launch of Convoy FS1, on 7 September Atlantic convoys were launched from both the Thames, coded OA, and the Mersey, OB. Once outside the U-boat danger area near the British coast, the convoys dispersed, as the smaller escorts were defenceless against the German surface raiders operating far out in the Atlantic. Homeward-bound merchant ships carrying war supplies, however, were convoyed all the way – most notably along the route from Halifax, Nova Scotia (coded HX) – and were often protected by heavy warships.

After the fall of France in June 1940, German U-boats moved to new French bases, increasing their range. As a result, convoys were extended across the Atlantic. This marked the beginning of a dangerous phase of the war, dubbed the Battle of the Atlantic by Winston Churchill. As the fighting progressed, new convoys became necessary, including routes to Malta and Russia (the ‘Arctic Convoys’). In total, 450 convoy series were run over the course of the war.