Up to 1943, with the German capital ships blockaded and ineffective, the Germans were nonetheless winning the war at sea: their U-boat arm had already sunk 12 million tons of merchant shipping. In the month of November 1942 alone they sank 117 ships, comprising 700,000 tons. Meanwhile the Allies’ best technological minds devised instruments and techniques to pinpoint and destroy the predators. From May 1943 the hunters became the hunters and the odds shortened on survival in the U-boat arm: on British estimation, the life expectancy of a German submariner was reduced now to fifty days. Out of 820 U-boats, 718 were destroyed in action; out of 39,000 men, only 7,000 survived the war.

What gives flesh to these horrifying statistics is this account by Peter ‘Ali’ Cremer of ‘his’ war. He was one of the three senior U-boat commanders to survive, finishing the war as commander of Dönitz’s bodyguard when the U-boat Commander-in-Chief took over from Hitler. Cremer evidently was a cat with nine lives – and with a remarkable ability to brink his U-boat back to base when it was so rammed, bombed, depth-charged and bullet-riddled that it could barely float. Few books convey the realities of the U-boat war as graphically as U333: it gives the reader an authentic periscope’s-eye view of the Battle of the Atlantic.