In World War II , following the Soviet invasion of Poland , dozens of ethnic Polish families were sent to Siberia by the NKVD in 1940 . Bortnica was one of many sites of the massacres of Poles and Jews committed between 1942 and 1945 by the death squads of OUN-UPA and the local Ukrainian peasants . The village was raided repeatedly in a process of ethnic cleansing . Farms were burned mostly at night . Jews kept a 24-hour vigil , because , unlike the Polish families who in the worst-case scenario could flee into the German – occupied cities , Jewish families had nowhere to run . Pitched battles with Ukrainian Insurgent Army were breaking out all the time . The bloodiest fighting broke out in Bortnica on Christmas Eve in 1943 , six weeks before the arrival of the Red Army . Fifteen Poles and eight Jews defending themselves against the invading force of 400 Ukrainian nationalists . Devoid of ammunition , the defenders fell back a day later . Half were killed in battle . A few escaped into the forest . In the Dubno County , the Polish self-defence against ethnic cleansing by OUN-UPA was more successful only in Pańska Dolina
massacres of Poles and Jews
Massacres of Poles in Volhynia and Eastern Galicia
Bortnytsia