lines to deter feared sabotage. In October 1929, the elderly Bristol Fighters were replaced with new Armstrong Whitworth Atlas aircraft, purpose-designed for the squadron's Army co-operation role, while these in turn were replaced by Hawker Audaxes in December 1931. In February 1937 it moved from Farnborough to RAF Odiham, soon re-equipping with the Hawker Hector, a more powerful derivative of the Audax. In January 1939, it discarded its Hector biplanes in favour of the new monoplane Westland Lysander. Second World War Shortly after the outbreak of the Second World War in 1939, the squadron moved to France as part of the British Expeditionary Force. Following Germany's invasion of France and the Low Countries on 10 May 1940, IV Squadron was frequently forced to change bases by the approach of the advancing German armies, being withdrawn to the UK on 24 May. Losses had been heavy, with 18 aircrew killed, while 60% of the groundcrew were lost. It continued in the coastal patrol and air-sea rescue role while training for its main Army co-operation role after returning to the UK. In 1942 the Squadron changed its mission from the Army co-operation role, where it would operate fairly low-performance aircraft from airstrips close to the front-line, to that of fighter-reconnaissance, receiving the more modern Curtiss Tomahawk and North American Mustang, soon with the latter soon replacing Tomahawk, flying low-level attack and reconnaissance flights against targets on the continent. In August 1943, it joined 2 Tactical Air Force in support of the planned invasion of Europe, changing to the pure reconnaissance mission in January, and replacing its Mustangs with Mosquito PR.XVI and Spitfire PR.XIs. It discarded its Mosquitoes in June, moved to France in August, and briefly supplemented its Spitfires with a few Hawker Typhoons for low-level reconnaissance. It retained its Spitfires at VE Day, moving to Celle in Germany to carry out survey operations in support of the British Army of Occupation until it was disbanded on 31 August 1945. Post War operations The squadron reformed the next day by renumbering 605 Squadron, a light bomber squadron equipped with Mosquitoes based at Volkel in the Netherlands. It re-equipped with de Havilland Vampire fighter-bombers in July 1950, replacing them with North American Sabres in October 1953. The Sabres were discarded in favour of the Hawker Hunter in July 1955, retaining these until the squadron disbanded at RAF Jever on 31 December 1960. Again,