The 27th Fighter Squadron (27 FS) is a United States Air Force unit. It is assigned to the 1st Operations Group and stationed at Langley Air Force Base, Virginia. The 27th Fighter Squadron is the oldest fighter squadron in the United States Air Force. Originally organized as the 21st Aero Squadron on June 15, 1917, the squadron was redesignated as the 27th Aero Squadron on June 23, 1917, and assigned to the 1st Pursuit Group in early 1918. The 27th entered World War I in the European theater where it served with distinction from March 1918 until the Armistice in November of that year.