 Complete the following phrase:  In 1918 as an officer of the General Staff he was the commander of the 1st Unit of the Army of UNR. In 1919 he became the chief of staff of the Independent Corps of Sich Riflemen. In 1920, after UNR leader Symon Petliuras alliance with Poland, he became the commanding officer of a regiment-sized 6th Ukrainian Infantry Division of the 2nd Polish Army under General Antoni Listowski. He commanded the unit in the April-June 1920 