No. 604 (County of Middlesex) Squadron RAuxAF
Active	17 March 1930 – 18 April 1945 10 May 1946 – 10 March 1957
Country	UK
Branch	Royal Air Force
Part of	Royal Auxiliary Air Force
Nickname(s)	County of Middlesex
Motto(s)	Latin:Si vis pacem para bellum (Translation: "If you want peace, prepare for war")[1][2][3]
Post-1951 aircraft insignia
Battle honours	France and Low Countries (1940) Dunkirk (1940) Battle of Britain (1940) Home Defence (1940–44) Fortress Europe (1943–45) Normandy (1944) France and Germany (1944–45)
Commanders
Honorary Air Commodore	Samuel Hoare, 1st Viscount Templewood (1932–1957)
Notable commanders	John Cunningham, Michael Hugh Constable-Maxwell, Frederick Desmond Hughes
Insignia
Squadron badge heraldry	Aseax No. 604 Squadron, being the County of Middlesex squadron, took part of the armorial bearings of the county, a seax, to commemorate that association[1][2]
Identification symbol	WQ (Jan 1939 – Sep 1939)[4] NG Sep (1939 – Apr 1945, 1949 – Apr 1951)[5] RAK (Jul 1946 – 1949)[6]

No. 604 Squadron RAF was a squadron of theRoyal Air Force noted for its pioneering role the development ofradar-controllednight-fighter operations. The squadron was established in March 1930 atRAF Hendon as a day-bomber squadron of theRoyal Auxiliary Air Force. In July 1934, the squadron transitioned to two-seat fighters. Shortly after the commencement of World War II in 1939, the squadron was reassigned to a night-fighter role.

No. 604 Squadron was initially disbanded in April 1945 as part of a reduction of theBritish Armed Forces near the end of the war. It was reformed as an auxiliary single-seat fighter squadron in May 1946, again at RAF Hendon. Final disbandment occurred in March 1957 with the dissolution of the Auxiliary Air Force.

No. 604 Squadron was established on 17 March 1930 atRAF Hendon as a squadron of the Royal Auxiliary Air Force.^[1][3] The squadron was initially assigned to the role of day-bombing and received its first aircraft (Airco DH.9As) in April 1930.^[7] The DH.9A was soon replaced by theWestland Wapiti in September 1930. Upon re-designation as a two-seat fighter squadron, No. 604 transitioned to theHawker Hart on 23 July 1934.Hawker Demons replaced the Harts in June 1935.^[8]

In early 1939 the squadron transitioned to the long-range fighter variant of theBristol Blenheim. No. 604 Squadron was activated on 24 August 1939 to operate long-range fighters fromRAF North Weald. The squadron spent the first several months of World War II flying defensive patrols in support of coastalconvoys.

The squadron was reassigned to a night-fighter role in late 1939 and was relocated toRAF Northolt in January 1940. By May 1940, the squadron had moved toRAF Manston. During the squadron's stay at RAF Manston thatFlying Officer Alistair Hunter andSergeant Gordon Thomas shot down aLuftwaffeHeinkel 115floatplane shortly after midnight on 18 June 1940, during the first major night raid over the United Kingdom.^[9] Following theDunkirk evacuation, the squadron was based atRAF Middle Wallop at the end of July 1940.

In early summer 1940, squadron aircraft were fitted withVHFradiotelephone equipment and Mark IIIaircraft interception (AI) radar. The former was part ofRAF Fighter Command policy, and greatly improved air-to-air and air-to ground communication. The AI radar equipment was fitted to assist the night fighter crews in locating German bombers at night. A new technological development, AI was not particularly reliable at this stage, and needed a third crew member to operate. The external antennas slowed down aircraft that were already considered of low performance for their role. Most AI operators were inexperienced and were forced to learn on the job, translating the information provided on the AI screens into instructions to enable their pilot to get close enough to visually locate and shoot down an enemy bomber.

Late in September 1940 the squadron received its firstBristol Beaufighter, equipped with four 20-mmHispano-Suiza HS.404 cannon under the nose and improved Mark IV AI radio-location equipment. As one of the few squadrons thus equipped, 604 Squadron provided night defence over the UK duringthe Blitz from late 1940 until mid May 1941, when mostLuftwaffe bomber units departed for involvement in theinvasion of Russia. By this time 50 air victories had been claimed by the squadron—fourteen by F/LJohn Cunningham.^[9]

In early 1943 the squadron began to switch over to night intruder operations. In February 1944, the squadron was allocated to the2nd Tactical Air Force and began conversion to thede Havilland Mosquito. Operations from Normandy began in August but the following month the unit returned to the UK, returning to the continent once again in January 1945. They remained there until disbanding at B.51 atVendeville,^[8][10] nearLille, France, on 18 April 1945.^[3][11] Some 127 air victories had been claimed by the Squadron during the war, 41 since May 1944.^[9] A notable member of the squadron, later awarded a posthumous George Cross, wasJohn Quinton DFC.

With the reactivation of theRoyal Auxiliary Air Force, 604 Squadron was reformed on 10 May 1946 at RAF Hendon as a day fighter squadron. It was initially equipped withSpitfire LF.16s but converted to jets in November 1949 whende Havilland Vampires arrived. These were replaced byGloster Meteors in August 1952 but this was only for a few years as the squadron was disbanded on 10 March 1957, along with all the flying units of the Royal Auxiliary Air Force.^[3][11]

• Bishop, Chris, ed. (2004).Encyclopedia of 20th Century Air Warfare. London: Amber Books.ISBN 978-1-904687-26-9.
• Bushby, John R. (1972).Gunner's Moon. Shepperton, Surrey: Ian Allan.ISBN 978-0-7110-0372-9.
• Chisholm, Roderick (1953).Cover of Darkness. London: Chatto and Windus.OCLC 1244740.
• Golley, John (1999).John "Cat's-Eyes" Cunningham: The Aviation Legend. Shrewsbury, Shropshire: Airlife Publishing.ISBN 978-1-84037-059-1.
• Rawnsley, Cecil Frederick; Wright, Robert (1957).Night Fighter. London: Collins.OCLC 1261586.

Wikimedia Commons has media related toNo. 604 Squadron RAF.

• 604 Squadron history on RAF website^{[dead link‍]}
• Squadron histories for nos. 600–604 sqn on RAFweb
• 604 in the Battle of Britain
• Traces of World War 2: RAF – No. 604 Squadron

• Royal Air Force aircraft squadrons
• Royal Air Force night fighter units
• Aircraft squadrons of the Royal Air Force in World War II
• RAF squadrons involved in the Battle of Britain
• Military units and formations established in 1930

• Articles with short description
• Short description is different from Wikidata
• Use British English from August 2015
• Commons category link is on Wikidata
• All articles with dead external links
• Articles with dead external links from April 2018
• Use dmy dates from August 2019