No. 123 (Army Co-operation) Squadron was formed on 15 January 1942 and flew army training operations in Ontario and Nova Scotia with the Westland Lysander. It was renumbered No. 439 (Fighter Bomber) Squadron on December 31, 1943 when it transferred to Wellingore, England and spent the war in England, France, Belgium, The Netherlands and Germany. It flew the Hawker Hurricane, and later the Hawker Typhoon.
They disbanded at Flensburg, Germany, on August 26, 1945. They reformed at Royal Canadian Air Force (RCAF) Station Uplands (CFB Uplands) on September 1, 1951, and went to 1 Wing North Luffenham on May 4, 1952, they then moved to 1 Wing Marville, France, on April 1, 1955. The squadron was equipped with the F-86 Sabre. They were deactivated between November 30, 1963, and February 28, 1964, and reactivated on March 1, 1964, as 439 Strike/Attack Squadron, equipped with CF-104 Starfighters. They moved with 3 Wing to Lahr, Germany on April 1, 1967, then to CFB Baden-Soellingen, Germany in 1971 as 439 Tactical Fighter Squadron. The squadron disbanded in November 1984 and reformed in November 1985 with the CF-18. They were disbanded at Baden-Soellingen on 15 May 1993 and reactivated shortly after at 3 Wing Bagotville as 439 Combat Support Squadron (French: 439e Escadron de soutien au combat). The squadron is now equipped with the CH-146 Griffon.