No. 12 Group of the Royal Air Force was a group, a military formation, that existed over two separate periods, namely the end of the First World War when it had a training function and from just prior to the Second World War until the early 1960s when it was tasked with an air defence role. History No. 12 Group was first formed on 1 April 1918 at RAF Cranwell, Lincolnshire, within No. 3 Area. It succeeded the Royal Navy's Central Depot and Training Establishment which had been training naval aviators at Cranwell since 1916. The first RAF General Officer Commanding was Brigadier-General H D Briggs who received the appointment on promotion from Captain in the Royal Navy. On 8 May 1918 the group transferred to Midland Area, and then to Northern Area on 18 October 1919. On 1 November that year the Group ceased to exist when it became the RAF (Cadet) College. The group was reformed on 1 April 1937 in Fighter Command at RAF Uxbridge as No. 12 (Fighter) Group. It was the group responsible for aerial defence of the Midlands, Norfolk, Lincolnshire and North Wales. Construction of a purpose built site at RAF Watnall, a non-flying station, was not completed until late 1940, after which operations were relocated from nearby RAF Hucknall. During the Second World War this group was the second most important group of Fighter Command, and as such, it received its share of attacks from the German Luftwaffe throughout the war. The commander of 12 Group during the Battle of Britain was Air Vice Marshal Trafford Leigh-Mallory, who was a rather ambitious man. Despite his length of service in the RAF, he was passed over for being named the Air Officer Commanding of the more vital 11 Group in favour of Air Vice Marshal Keith Park. Leigh-Mallory felt himself slighted over this and his relations with Park were poisoned thereafter. As well as regional defence, 12 Group were also supposed to provide fighter cover for 11 Group airfields during the Battle of Britain, but several times, these fields were left undefended. When Park complained about it, Leigh-Mallory responded that in order to test his Big Wing theory (espoused by Squadron Leader Douglas Bader), more time was needed to get the necessary squadrons airborne. The Big Wings met with mixed success, enough for the Air Ministry to use it as an excuse to oust