The unit was created on May 19, 1921 out of two previously-existing units, the
Polish 7th Air Escadrille and the
Polish 18th Air Escadrille of the 1st Air Regiment. Initially it was manned mostly by the American veterans of the earlier unit, including
Cedric Fauntleroy. However, soon afterwards most of the American pilots returned home and the unit was manned with Polish officers. Nonetheless, it retained the roundel and the traditions of the Polish-American unit. In 1934 the unit was the first to receive the then-modern
PZL P.11c fighters. In 1936 the escadrille was stationed in
Sarny and was providing air cover for a construction of border fortifications at the frontier with the
Soviet Union. During one of the sorties Lt.
Witold Urbanowicz, later to become one of the fighter aces of World War II, downed a Soviet
Polikarpov R-5 biplane reconnaissance aircraft flying a reconnaissance mission over the area. In 1939 it was attached to the
Pursuit Brigade, Palusiński himself was wounded by enemy fire. Later that day another bombing raid on Warsaw was intercepted, this time covered by
Messerschmitt Bf 109 fighters. During the air battles over Warsaw the escadrille's commanding officer managed to down one enemy fighter, but was then shot down and wounded. The command was taken over by his deputy, Lt. Januszewicz. The following day the escadrille did not encounter any enemy formations. On September 3 a flight from the escadrille, providing air cover for
Col. Stefan Pawlikowski intercepted a formation of enemy Bf 110 fighters over
Wyszków. Lt. Januszewicz and
Corporal Karubin downed two enemy fighters. However, at the same time another flight led by Ferić was dispersed and had to return to base. One of its pilots did not return to the escadrille until September 10. Altogether during the campaign the unit downed 8 enemy planes (other sources mention 7½) while losing 9 of its own
PZL P.11c fighters. After the
Soviet invasion of
Poland on September 17, the unit was evacuated to
Romania together with its 4 remaining fighters. From there the majority of the pilots were able to get to
France and the
United Kingdom, where many joined the
Polish Air Forces in exile. The traditions of the escadrille, as well as its predecessor, was then continued by the
No. 303 Polish Fighter Squadron, one of the most successful Allied fighter units of the war. == Crew and equipment ==