The Western Approaches Tactical Unit (WATU) was a unit of the British Royal Navy created in January 1942 to develop and disseminate new tactics to counter German submarine attacks on trans-Atlantic shipping convoys. It was led by Captain Gilbert Roberts and was principally staffed by officers and ratings from the Women's Royal Naval Service (Wrens). Their primary tool for studying U-boat attacks and developing countermeasures was wargames. After the U-boat threat to merchant shipping was defeated, WATU continued to develop anti-submarine tactics for later stages of the war, including Operation Overlord and the Pacific War. WATU trained naval officers in its tactics by hosting week-long training courses in which the students played wargames. WATU formally ceased operations at the end of July 1945.
Background During World War I, German submarines (U-boats) sank merchant ships in the Atlantic Ocean so as to deny supplies to Germany's enemies in Europe. Britain reacted by organising the merchant ships into convoys which were escorted by warships armed with depth charges. This strategy proved effective at repelling U-boats. During the inter-war years, Germany secretly developed new submarine tactics to counter the convoy system. The products of this research were the "wolfpack" tactics, wherein submarines would attack convoys in groups, exploiting the weaknesses of the convoy system, and new advances in submarine technology. The British, by contrast, had neglected to study submarine tactics during the inter-war years. They entered World War II assuming that the U-boats would operate much as they had during the previous war, unaware that the Germans would come at them with new tactics.
As soon as Britain declared war on Germany (3 Sept 1939), Germany sent its U-boats to attack transatlantic shipping. The U-boats had a devastating effect. In 1938, Britain had received 68 million tons of imports, but in 1941 the U-boats reduced this to 26 million., Why the Allies Won. p. 31 Britain was not a self-sufficient nation, and eventually its reserves of food would run out and it would be forced to capitulate to prevent a famine.Parkin (2019). A Game of Birds and Wolves, chpt. 3: "'Unless something was done in the Battle of the Atlantic,' Roberts was told, 'we were going to lose [the war], merely because vital food and war supplies would not arrive.'" In March 1941, Prime Minister Winston Churchill declared that Britain was fighting "the Battle of the Atlantic", and made anti-submarine warfare a top priority.
The Royal Navy understood from intercepted radio transmissions that the U-boats were operating in coordinated groups but did not know the specifics of their tactics.Parkin (2019). A Game of Birds and Wolves, chpt. 8: "While the British could see from intercepted radio transmissions that U-boats were increasingly working together, providing the German vessels with safety in numbers, the specifics of their highly effective tactics could only be guessed at."
Establishment and Mission On 1 January 1942, Admiral Cecil Usborne assigned Commander Gilbert Roberts to establish a wargaming unit at the Western Approaches Command in Liverpool, to analyze the submarine attacks and develop defensive tactics.Parkin (2019). A Game of Birds and Wolves, chpt. 8: "On the first day of 1942, Roberts was told to report to the Admiralty offices with an overnight bag. On arrival he met two of the navy's most senior officers, the Second Sea Lord, Sir Charles Little, and Admiral Cecil Usborne, the former director of naval intelligence, now an aide to Winston Churchill. Usborne was responsible for overseeing the development of anti-U-boat weapons." Roberts had designed naval wargames during a two-year stint at the Portsmouth Tactical School, using them to develop new strategies and tactics. Additionally, Roberts was a communicator who would be able to train commanders in the tactics he was to develop.Parkin (2019). A Game of Birds and Wolves, chpt. 8: "Churchill's aide believed that Roberts, who had shown himself to be a talented strategist in Portsmouth and an enthusiastic proponent of games as a way to prepare for war, was the ideal person to evolve anti-U-boat tactics. Moreover, as a gifted communicator he was qualified to train escort commanders in those tactics."
Roberts moved to Liverpool to set up his tactical unit on the top floor of the Western Approaches headquarters. This assignment officially began on 23 February 1942. Most of the staff at Western Approaches were women from the Women's Royal Naval Service (colloquially referred to as "Wrens"), and likewise Roberts recruited most of his staff from the Wrens. A total of sixty-six Wrens served at WATU from 1942 to 1945.Parkin (2019). A Game of Birds and Wolves, Postscript: "By 1945, a total of sixty-six Wrens had completed the course in order to become staff at WATU or its sister units."
Roberts and his team reviewed battle reports from convoy escort commanders, recreated the battles in wargames in order to deduce how the U-boats were operating, and then devised tactics by which the escorts could defeat the U-boats. Their first product was a tactic codenamed Raspberry (see below). As well as devising tactics, WATU also trained naval officers in their use by having them participate in wargames. The training course lasted six days, from Monday to Saturday, and was held every week from February 1942 to the last week of July 1945. Up to fifty officers at once took the course.Parkin (2019). A Game of Birds and Wolves, chpt. 12: "Each course, which lasted from Monday to Saturday, and which ran weekly without interruption from the first week of February 1942 to the last week of July 1945, involved up to fifty officers at once." WATU not only trained British officers, but also officers from other countries such as Canada, the United States, New Zealand, Norway, South Africa, Poland, and Free France.Parkin (2019). A Game of Birds and Wolves, chpt. 12, fn 1: "Roberts recorded that on Sundays the team would often be called upon to give demonstrations to visiting Americans."
In May 1943, Admiral Karl Doenitz ordered the U-boats to withdraw from the Atlantic, allowing merchant convoys to pass unmolested.
By 1944, WATU's existence was public knowledge. A journalist visited WATU in January 1944 to observe a wargame and published a short article in The Daily Herald.The Daily Herald. 17 January 1944 An account of WATU's work appeared in Illustrated magazine the following month.
WATU continued to develop anti-submarine tactics and train officers until the end of the war. It officially ceased operations at the end of July 1945. It had trained close to 5,000 officers over its lifetime.Parkin (2019). A Game of Birds and Wolves, postcript
Headquarters Western Approaches Command was an operational command of Britain's Royal Navy, tasked with safeguarding British shipping in the Western Approaches (the seas to the west of Ireland and Britain). Initially headquartered in Plymouth, on the southern coast of Britain, it was moved north to Liverpool in February 1941. After France had fallen to the Germans, North Atlantic shipping convoys had been diverted around the north of Ireland to evade the Kriegsmarine (German navy). Relocating Western Approaches Command to Liverpool sped up communications. Its headquarters was Derby House, a building located behind Liverpool's town hall; today the headquarters is Western Approaches Museum. The top floor, comprising eight rooms, was allocated to WATU.Parkin (2019). A Game of Birds and Wolves, chpt. 10: "Roberts was to be given the entire top floor of Derby House, [...] comprising eight rooms." Most of the staff at Western Approaches HQ were women from the Women's Royal Naval Service. Colloquially, they were referred to as "Wrens". When Roberts arrived at Western Approaches in January 1942, its commander-in-chief was Admiral Percy Noble, who was replaced by Admiral Max Horton in November 1942.
Staff A total of sixty-six women from the Women's Royal Naval Service (Wrens) served at WATU from 1942 to 1945.
Captain Gilbert Roberts - Director of WATU. Once commanded a destroyer but contracted tuberculosis in late 1938 and was barred from serving at sea. Mary Poole - WRNS officer. The first female officer to take the WATU course. Laura Janet Howes - WRNS officer. Born in Antigua. Mathematical prodigy. Nicknamed "Bobby". Elizabeth Drake - WRNS officer. When WATU was established, she was already working at Derby House as a plotter. Nancy "Nan" Sofia Wailes - WRNS officer. Born in Kingston upon Hull, joined the Wrens in 1941. She was a passionate hockey player, and was selected for her understanding of team tactics. Jean Laidlaw - WRNS officer. Scottish. Former Sea Ranger and chartered accountant. Janet Okell - WRNS rating. She was only 19 years old when she joined WATU in January 1942. She served at WATU for the whole duration. Okell was initially trained as a plotter, but she was soon participating in wargames as a player, commanding U-boats and escort ships alike. June Duncan (1924-2014) - WRNS rating. One of WATU's longest serving members, in the 1950s, became one of Britain's top fashion models. Dorothy N. G. "Judy" Du Vivier - WRNS Mary (née Carlisle) Hall - WRNS Elizabeth Hackney - WRNS Doris Lawford - WRNS Pauline Preston - WRNS
Overview of the wargames Gilbert Roberts was first introduced to wargaming during a stint at the Portsmouth Tactical School from 1935 to 1937. Roberts took to wargaming with great enthusiasm, and developed his own rulesets. Roberts' wargames were based on the wargames developed by Fred T. Jane in 1898 (Jane Naval Wargame and Fighting Ships).Parkin (2019). A Game of Birds and Wolves, chpt. 7: "The progenitor of the wargame on which Roberts based his games in Portsmouth was Fred Jane [...] It was a version of the Jane Naval Wargame that Roberts adapted at his posting in Portsmouth" Despite the strong effect that U-boats had during World War I, Roberts' wargames at Portsmouth did not simulate submarine warfare, nor attacks on merchant convoys. He later said "Submarines were not mentioned ... Nor were convoys and attacks on them. Nobody connected Hitler's rise ... to the possibility of another Battle of the Atlantic. Nor did I, to be absolutely fair."Parkin (2019). A Game of Birds and Wolves, chpt. 7 However, Roberts told the Royal United Services Institute in 1947 that before the war "In the Tactical School, a short game was played in which a convoy was escorted by a fleet and the enemy force included some submarines."