It has long been the practice in wartime for the British government to requisition civilian vessels for war service. Often these vessels are used in the logistics role supporting the Royal Navy at sea or the British Army and Royal Air Force in foreign lands. The practice has been used as late as the 1982 Falklands War where perhaps most famously the ocean liner Queen Elizabeth II was used to ferry over 3000 troops to the South Atlantic. Using civilian ships in wartime is a precarious business at best. They are seldom designed with the same level of protection a warship is afforded making them very vulnerable and their vital role in supporting the war effort makes them highly prized targets for the enemy.
One such civilian ship taken over for use by the Royal Navy was the Cunard White Star Line passenger ship the Laurentic. Requisitioned by the Admiralty a week before Germany invaded Poland on September 1st 1939 the vessel was put in to dock for conversion to an armed merchant cruiser which was completed in a remarkably short space of time. HMS Laurentic F51 was accepted in to service on October 15th 1939. As part of her conversion she was armed with seven Breech Loading 5.5inch (140mm) Mk I guns and three QF 4inch (102mm) Mk.XVI naval guns. She was also fitted with a quantity of depth charges for use against submarines.
The vessel was, like many of her kind, primarily employed on patrol and escort duties; armed merchant cruisers were effectively the last line of defence with the Royal Navy’s main fleet and aircraft being the first. Her start to the war was relatively uneventful but all that changed on the evening of November 3rd 1940. A little after 2140 hours her commanding officer, Capt E.P. Vivian RN, was informed that the radio room had received a distress call from an unescorted merchantman, the Casanare, stating it had been attacked by a U-Boat. Along with another armed merchant cruiser, HMS Patroclus, Laurentic raced to the scene west of Ireland at a place called Bloody Foreland.
Unknown to Captain Vivian and his men they were about to face off against one of Germany’s greatest U-Boat aces, the brash and skilled Kapitänleutnant Otto Kretschmer (known as “Silent Otto”) and his crew of U-99. Kretschmer’s attack had been a textbook example of U-Boat warfare, catching the Casanare completely by surprise. The torpedo struck just aft of the vessel’s bridge and she began to list heavily enough for the crew to begin abandoning ship. The wireless operator aboard U-99 suddenly found his headset alive with messages between their victim and the two approaching ships all of which were transmitted uncoded and in plain language.
Kretschmer continued to shadow the sinking Casanare while surfaced and it was not long before he detected the two ships coming to its aid. Picking his moment carefully, Kretschmer waited for the Laurentic to come in to his sights and at 2250hrs he unleashed his deadly arsenal on his second unsuspecting victim of the night (this early in the war few ships had radar to detect a surfaced U-Boat at night but by 1945 this kind of operation would have been suicide for a U-Boat commander). Launched from a distance of one and a half kilometres and incredibly while the U-Boat was turning the torpedo struck the Laurentic amidship near the boiler room tearing open a gaping hole in her side. Kretschmer watched the ship expecting it to sink and indeed a number of her crew had leapt overboard in the chaos of the blast but as the smoke dissipated the Laurentic proved that she was not done for yet and remained stubbornly afloat.
Kretschmer made two more attacks on the Laurentic, one at 2320hrs and another at 2330hrs with the range now having decreased to just 250m. The crew of the Laurentic briefly spotted the U-Boat on the surface and began shelling the submarine which quickly slipped away. The Laurentic was now heavily damaged and was riding much lower in the water than it should be convincing Kretschmer that the ship was finally done for and so he turned his U-Boat away to assess his situation.
In the meantime, HMS Patroclus had arrived on station and began efforts to rescue the crew of the Laurentic many of whom were abandoning the ship. The Patroclus’ Captain, William Wynter, ordered that two depth charges be launched over the side in an effort to frighten the U-boat away. He couldn’t have known that Kretschmer was still on the surface unseen in the night. Believing he had successfully drove off the U-Boat, Wynter’s crew began to rescue their comrades but Kretschmer had come about and at 0022hrs the Patroclus was hit by a torpedo from U-99 killing an unknown number of men aboard a lifeboat from the Laurentic that was being hauled aboard at the time. Like the Laurentic the Patroclus refused to sink and twenty minutes later at 0044hrs a second torpedo was launched in to the ship. The torpedo malfunctioned and missed its aim point hitting below the foremast. No doubt gritting his teeth Kretschmer fired a third torpedo at 0118 hrs but as he did so the British lookouts spotted the U-Boat and Kretschmer found his vessel taking fire forcing him to flee yet again.
Dumbfounded by his enemy’s refusal to sink, Kretschmer searched for his first target, the Casanare, to confirm it had indeed sunk. Two lifeboats bobbing in the water at her last known position offered the proof he was looking for when suddenly the air around him growled with the sound of aeroengines as an RAF Shorts Sunderland flying boat appeared over the scene. Kretschmer ordered his U-Boat to dive and the RAF aircraft was unable to launch its weapons but remained on station trying to locate the submarine.
Kretschmer used his time submerged wisely and reloaded the torpedo tubes. With the sound of the Sunderland’s engines dissipating he felt confident enough to surface at 0330 hours. Rather arrogantly he went back to the site of his attack on the two armed merchant cruisers and saw that Laurentic and Patroclus had still yet to sink! At 0435hrs he fired a fourth torpedo at Laurentic which struck astern. The blast ignited the depth charges stored in that area resulting in a huge explosion. The Laurentic’s luck ran out and the ship began to sink by the stern disappearing forever.
Kretschmer then turned on the Patroclus but as he did so his own lookouts spotted a destroyer, HMS Hesperus, approaching on the horizon. Rather than be satisfied with sinking the Casanare and the Laurentic he made a hasty attack on the Patroclus. At 0516hrs a fifth torpedo struck the ship fired from U-99 but the British ship refused to go down one last time prompting Kretschmer to fire a sixth torpedo. That was the end of the Patroclus and the hull crumbled into pieces before finally sinking. 114 sailors had been killed in the whole incident.
Kretschmer immediately ordered his U-Boat to dive as the destroyer zeroed in on him. Kretschmer and his men now paid for their victory as they were repeatedly depth charged by the Hesperus but the destroyer failed to score a direct hit and Kretschmer returned to Germany a hero.
So just what was the secret behind the Laurentic and the Patroclus that kept them afloat for so long? Was it excellent damage control techniques? Perhaps it was superb craftsmanship in the construction of the two vessels? Actually it was neither. It was in fact the placing of thousands of empty oil drums inside the hull of the ship. This dramatically increased the overall buoyancy of the vessels which meant that despite several gaping holes in the hull the barrels kept the vessels afloat making them very tough to sink.