Created by former members of the Sich Riflemen and the Galician Nationalist Army (particularly, the 6th Rava Brigade) in August 1920 in Prague, the UVO was a secret military and political movement.

Among such attempts were a failed assault on Chief of State Józef Piłsudski and Voivod of Lwów Kazimierz Grabowski on September 25, 1921, the successful murder of Ukrainian poet Sydir Tverdohlib and assassinations of Ukrainian activists Wasyl Pihulak and Iwan Bachmaszczuk in 1922,[7] as well as a failed attack on Poland's president Stanisław Wojciechowski in 1924 and the Nonpartisan Bloc for Cooperation with the Government (BBWR) deputy chairman Tadeusz Hołówko.

It organized three bomb attacks on the Eastern Trade Fair in Lwów in 1929, bombings of train stations, railway tracks, pumping stations, burnt and blown up police buildings (e.g. in Yavoriv, Gródek, Uhnów, Lubaczów) and Polish households; it was also active in destruction of telegraph, telephone poles and committed a number of expropriation attacks - amongst them - the robbery of 100,000 złoty (then the equivalent of 20,000 dollars) from a Lwów Post Office in 1925.

The Germans supported military training of Ukrainian Nationalists in Eastern Prussia, whereas the Free City Danzig (Gdańsk) became an important transit place for money, arms and ammunition.

[11] There had been several previous attempts to provide former Ukrainian nationalist fighters with official veteran status, especially during the 2005-2009 administration President Viktor Yushenko, but all failed.