The Arctic convoys travelled from the United Kingdom and the United States to the northern ports of the Soviet UnionArkhangelsk and Murmansk. The convoys ran from Iceland north of Jan Mayen Island to Arkhangelsk when the ice permitted in the summer months, shifting south as the pack ice increased and terminating at Murmansk. However, as the air gap over the North Atlantic closed, Huff-Duff improved, airborne centimetric radar was introduced and convoys received escort carrier protection, the scope for commerce raiding diminished. Convoy PQ 18 departed Loch Ewe on September 2 with destination Archangelsk....