The 27th was initially formed as Company K, 3d Provisional Aero Squadron on 8 May 1917 at Kelly Field, Texas. On 15 June, Company K was re-designated as the 21st Aero Squadron. However, another 21st had been organized at Rockwell Field, California and on 23 June, the squadron was re-chartered as the 27th Aero Squadron. As Company "K", and later as the 27th, the squadron was initiated into the Army with close order drill, along with the labor of clearing cactus from the grounds of Kelly Field #2, and erecting a tent city, enduring the hazards of snakes and inclement weather according to the squadron historian at the time.