In 1755, Kościuszko began attending school in Lubieszów but never finished due to his family's financial straits after his father's death in 1758. Poland's King Stanisław August Poniatowski established a Corps of Cadets ("Korpus Kadetów") in 1765, at what is now Warsaw University, to educate military officers and government officials. Kościuszko enrolled in the Corps on 18 December 1765, likely thanks to the Czartoryski family's patronage. The school emphasized military subjects and the liberal arts, and after graduating on 20 December 1766, Kościuszko was promoted to "chorąży" (a military rank roughly equivalent to modern lieutenant). He stayed on as a student instructor and, by 1768, had attained the rank of captain.