HMS Aubrietia (K96): The Corvette That Really Captured the Enigma Machine

An Unremarkable Corvette, at First

HMS Aubrietia was a Flower-class corvette built by George Brown and Company at Greenock, laid down on 27 October 1939, launched on 5 September 1940, and completed on 23 December that year. She displaced 940 tons, carried a single 4-inch gun and depth charge throwers, and was, in almost every respect, an entirely typical example of a class built cheaply and quickly to plug an urgent wartime gap in convoy escort numbers. Nothing about her specification suggested she would go on to play a part in one of the most significant intelligence coups of the entire Second World War.

The Real Story Behind U-571

On 9 May 1941, while escorting Convoy OB 318, Aubrietia spotted the periscope of the German submarine U-110 and depth charged it, forcing the submarine to surface in a badly damaged state. Boarding parties from HMS Bulldog then captured the submarine's Enigma cipher machine and its codebooks intact, a genuinely pivotal moment for Allied codebreaking efforts at Bletchley Park and one of the most significant intelligence victories of the entire Battle of the Atlantic. It is worth noting, with a certain wry satisfaction, that this was a wholly British operation, involving Aubrietia and Bulldog, roughly six months before the United States even entered the war, whatever a certain well-known Hollywood submarine film might have later suggested to the contrary.

Eighty-Five Convoys and a Second Success

Aubrietia went on to a genuinely relentless convoy escort career, protecting shipping across the Atlantic, the Mediterranean and off North Africa, including during Operation Torch, and is credited with escorting no fewer than 85 convoys between January 1941 and April 1945, an extraordinary tally that speaks to just how central these small, unglamorous corvettes were to keeping Britain supplied throughout the war. She had a second brush with U-boat hunting success in May 1944, taking part in attacks on the German submarine U-731 near Gibraltar.

A Norwegian Retirement

Aubrietia was decommissioned on 29 July 1946 and sold in 1948 to a Norwegian company, renamed Arnfinn Bergan, going on to a further merchant career before finally being scrapped in Norway in December 1966, a quiet, ordinary end for a ship whose single most famous action had, in fact, been anything but ordinary.