<p>In the autumn of 1944 the Second World War was coming to an end. In the Atlantic the U-boats had been beaten back through a massive programme of Allied shipbuilding combined with tactical, technological and intelligence improvements. The threat to Allied shipping had diminished. But it had not disappeared, and a lone U-boat on its first active patrol slipped into the North Channel; in just a few days five ships lay broken on the seabed includi...