The U-30 crew learning that they had just hit Athenia, an unarmed civilian ship full of women and children, were horrified that they had just committed a warcrime. Lemp swore his crew to secrecy and ordered them to never speak of the attack. He also altered the ship’s official log to erase any connection with the attack.

The Mid-Atlantic gap is a geographical term applied to an undefended area of the Atlantic Ocean during the Battle of the Atlantic in the Second World War. The region was beyond the reach of land-based RAF Coastal Command anti-submarine warfare (ASW) aircraft. This resulted in many merchant shipping losses to U-boats. The gap was eventually closed in May 1943, as growing numbers of Very Long Range Liberators (VLR) and escort carriers became available and as basing problems were solved. The Mid-Atlantic gap was an area outside the cover by land-based aircraft; those limits are shown with black arcs (map shows the gap in 1941). Blue dots show destroyed ships of the Allies

In May 1943, U-boat strength reached its peak, with 240 operational U-boats, of which 118 were at sea, yet the sinking of Allied ships continued to decline.[2] May 1943 also had the greatest monthly losses suffered by U-boats up to that time, with 41 being destroyed, 25 per cent of the operational U-boats.[3] The month opened with the battle for Convoy ONS 5, which was costly for both sides, with the loss of 13 merchant ships and six U-boats. The tactical improvements of the escorts began to take effect; the next three convoys that were attacked resulted in seven ships sunk and an equal number of U-boats. Five U-boats were sunk attacking Convoy SC 130, with Admiral Karl Dönitz's son, Peter, among those lost aboard U-954, while no convoy ships were lost.[4] Allied losses in May were 58 ships of 299,000 long tons (304,000 t), of which 34 ships of 134,000 long tons (136,000 t) were lost in the Atlantic.

During May there had been a drop in Allied losses, coupled with a tremendous rise in U-boat losses; 18 boats were lost in convoy battles in the Atlantic in the month, 14 were lost to air patrols; six of these in the Bay of Biscay. With losses in other theatres, accidents and other causes, the total loss to the U-boat arm in May was 43 boats. On 24 May 1943, Admiral Dönitz, shocked at the defeat suffered by the U-boats, ordered a temporary halt to the U-boat campaign; most were withdrawn from operational service. The U-boats were unable to return in significant numbers until autumn and never regained the advantage.

This month had the most losses suffered by the U-boat Arm in the war so far, nearly three times the number of the previous highest, and more boats than had been lost in the whole of 1941. Equally significant was the loss of experienced crews, particularly the junior officers, who represented the next generation of commanders. Black May signalled a decline from which the U-boat arm never recovered; efforts were made over the next two years but the U-boats were never able to re-establish their threat to Allied shipping.

On 20 August, after a boiler cleaning, the ship left Southampton to relieve the corvette HMCS DRUMHELLER on patrol duty to the eastward of the swept channel where it divided in mid-channel for the British and American beach heads. At 0943Z on the 21st, she had covered about two-thirds of the distance to the patrol area. She was steaming at fourteen knots on a southerly course.

Four minutes later, about twenty-five miles southeast of St. Catherine’s Point on the Isle of Wight, ALBERNI was rocked by a shattering explosion. In less than ten seconds, she was awash from the funnel aft, listing to port and sinking fast by the stern. In another twenty seconds, she was gone. What had been confidently steaming on the surface moments before had completely vanished.Four minutes later, about twenty-five miles southeast of St. Catherine’s Point on the Isle of Wight, ALBERNI was rocked by a shattering explosion. In less than ten seconds, she was awash from the funnel aft, listing to port and sinking fast by the stern. In another twenty seconds, she was gone. What had been confidently steaming on the surface moments before had completely vanished.

At the moment of the explosion, all hands, with the exception of those on watch, had been in the messdecks. The inrush of water as the ship went down trapped them. Those who survived had no time to release carley floats. Many were without life belts and could stay afloat only by clinging to some bit of flotsam. For forty-five minutes, they struggled to keep afloat in fairly heavy sea. At the end of that time, just when many were ready to give up, the HM Motor Torpedo Boats Numbers 469 and 470 appeared. The welcome rescuers fished them out of the water and landed them at Portsmouth. None was severely hurt.

Four officers and 55 men went down with ALBERNI. Three officers, including the Commanding Officer, and 28 men survived. There has never been complete agreement as to whether the ship had been mined or torpedoed, but, post-war German publications state that she was sunk by U-480 (Oberleutnant Hans-Joachim Förster) with an acoustic torpedo. U-480 was sunk with all hands on 24 February 1945 by HMS Duckworth and HMS Rowley.