A powerful underground Ukrainian nationalist movement arose in eastern Poland in the 1920s and 1930s, which was formed by Ukrainian veterans of the Ukrainian-Soviet war (including Yevhen Konovalets, Andriy Melnyk, and Yuriy Tyutyunyk) and was transformed into the Ukrainian Military Organization and later the Organisation of Ukrainian Nationalists (OUN). The movement attracted a militant following among students. Hostilities between Polish state authorities and the popular movement led to a substantial number of fatalities, and the autonomy which had been promised was never implemented. The pre-war Polish government also exercised anti-Ukrainian sentiment; it restricted rights of people who declared Ukrainian nationality, belonged to the Eastern Orthodox Church and inhabited the Eastern Borderlands. The Ukrainian language was restricted in every field possible, especially in governmental institutions, and the term "Ruthenian" was enforced in an attempt to ban the use of the term "Ukrainian". Despite this, a number of Ukrainian parties, the Ukrainian Catholic Church, an active press, and a business sector existed in Poland. Economic conditions improved in the 1920s, but the region suffered from the Great Depression in the early 1930s.