From the Centralnego Archiwum Wojskowego (Central Military Archive) Warsaw a copy of the original letter from Merian Cooper to General Józef Piłsudski dated 29 April 1919 offering his services to the Polish commander and Head of State.
In late 1919 eight American volunteers, including Major Cedric Fauntleroy and Captain Merian C. Cooper, arrived in Poland from France where in September 1919 they had been officially named the Kościuszko Squadron (after the Polish American hero Tadeusz Kościuszko) with Major Fauntleroy as its commander.
The Kościuszko Squadron was the first air squadron to use a railway train as a mobile flying base with specially designed railroad cars that could transport their aircraft as the front moved and developed. The train also included the squadron's operational headquarters, aircraft spares and repair workshops and living quarters.
The Kościuszko squadron flew 400 missions. The name was famously used for Polish No. 303 Squadron which was responsible for the highest number of kills of any RAF squadron during the Battle of Britain. Although part of the RAF, 303 squadron was a formation of the Polish Air Force (PAF) which operated under the principal authority of the Polish government-in-exile.