As a direct result of the capture of the British steamer City of Baghdads secret code books by the German surface raider Atlantis in July 1940 the Nazis were able to de-cypher Admiralty convoy plans with deadly effect. Admiral Doenitz aware of the movements of the Allied convoys marshalled as many of his U-boats as possible. This book describes the resulting appalling Allied losses suffered by four convoys during the Autumn of 1940. The first convoy SC2 consisting of fifty-three merchantmen was attacked in early September by four U-boats. Due to poor weather only five ships were lost. Shortly afterwards HX72 sailing from Nova Scotia lost eleven of its forty-one ships to five Type VIIC U-boats. Top Aces Otto Kretschremer & Joachim Schepke who penetrated inside the columns accounted for nine. No less than nine U-boats attacked SC7 in October 1940. Of thirty-five merchantmen a staggering twenty were lost. Despite being a fast convoy with ten escorts HX79 also fared terribly losing twelve ships. In total forty-eight merchantmen were sunk & seven more damaged without any U-boat losses at all.A superbly researched & authoritative account of the darkest hours of the Battle of the Atlantic The Wolf Packs Gather is a tragic account of unprecedented losses of seamen ships & cargo from these merciless attacks on the four convoys. The Author a much published & distinguished historian & Merchant Navy captain is well qualified to describe not only the German tactics but the inadequacies of the Allied counter-measures.