Born in 1867 in Galicia, Austria–Hungary, he was the grandson of Polish playwright Aleksander Fredro and brother of Andrey Sheptytsky, Metropolitan Archbishop of the Ukrainian Greek Catholic Church. Szeptycki joined the Austro-Hungarian Army, where he attained the rank of colonel. In 1914 he joined the Polish Legions, where he became commander of the Third Brigade, and from November 1916 to April 1917 commander of the entire Polish Legions formation. Following the Oath Crisis he commanded the German-aligned Polnische Wehrmacht. Until February 1918 he was Austro-Hungarian governor general of Lublin, but resigned in protest when Germany turned Chełm and the surrounding area over to the Ukrainians. He joined the newly recreated Polish Army in November 1918, and replaced General Tadeusz Rozwad