Facts. After the fall of the Ukrainian People’s Republic, Volyn and most other lands inhabited by both Poles and Ukrainians found themselves within Poland’s borders. While the state tried to reach out to its Ukrainian minority, it was unable to find the right policy to manage the multiethnic state, and the rights of Ukrainians were not respected. With no country of their own, Ukrainians became increasingly radicalized under Polish policies, leading to the foundation of the Organization of Ukrainian Nationalists (OUN) in 1929. The 1930s were marked by growing confrontation between the two sides.
World War II significantly changed the landscape, further deteriorating relations. Three main causes led to the escalation of hostilities. Firstly, the question of whom Eastern Galicia and Volyn belonged to was once again open. Secondly, both occupying forces – but especially the Germans – showed the locals how ethnic problems can be solved, through expulsion and extermination. Thirdly, Polish and Ukrainian elites were among the first casualties, demoralizing both communities.
In these conditions the Ukrainian Insurgent Army (UPA), an armed formation established by the OUN-B (the fraction led by Stepan Bandera), decided to proceed with the cleansing of lands they saw as Ukrainian, that were to join an independent Ukraine after the war. The new Ukrainian state, in line with the ideology of Ukrainian nationalists, was to be ethnically pure.