Buchach remained a part of Austria and its successor states until the end of the First World War in 1918. The town was briefly a part of the independent West Ukrainian People's Republic before it was captured by the Republic of Poland in July 1919 after Ukrainian-Polish War. Also, between August 10 and September 15, 1920, it was occupied by the Red Army (see Polish-Soviet War). In the Second Polish Republic, Buchach was the seat of a county (powiat) in Tarnopol Voivodeship. In the 1920s, Buchach was inhabited by Jews (~60%), Poles (~25%), and Ukrainians (~15%).