After the German defeat in Galicia, Fedun rapidly rose through the ranks of the OUN, being appointed director of the Main Propaganda Cell in 1946.

Petro Mykolaiovych Fedun was born on 23 February 1919, in the Galician village of Shnyriv,[1] the middle child between elder sister Hanna and younger brother Vasyl.

[3] Fedun joined the youth branch of the Organisation of Ukrainian Nationalists in 1936, alongside fellow Shnyriv natives Bohdan Panasiuk and Wasyl Jaszczun [uk].

Following the Soviet annexation of Eastern Galicia and Volhynia, Fedun was forced to leave university after being conscripted into the Red Army.

[6] Fedun's Red Army service remains a matter of ongoing debate in Ukrainian historiography, particularly regarding his role in the Winter War.

[11] He also became the leader of the Union of the Ukrainian Nationalist Studentry, and from 1943 to 1944 edited the OUN Youth's journal, Yunak, under the pseudonym of "Vol.".

[7] Later, he also joined the activities of the Bandera-aligned Ukrainian Insurgent Army (UPA), becoming head of the political education directorate of the Western Operational Group in March 1944.

He began working as editor of three different propaganda journals, and travelled into the Carpathian Mountains to train young members of the OUN in ideology.

He additionally became a member of the Main Military Staff of the Ukrainian Insurgent Army [uk] focusing on political education.

[12] At the same time as the German defeat, Fedun joined the Ukrainian Supreme Liberation Council,[14] a political body established by the OUN-B.

[11] According to historian Volodymyr Marchuk, after the death of Yosyp Pozychaniuk [uk][14] in December 1944,[15] Fedun became leader of the Main Propaganda Cell and Information Service.

Hinda states that at this time Fedun had acquired a reputation among members of the OUN underground for his oratical and journalistic skills.

Simultaneously, the directive instructed educators to describe the United Nations as a reactionary and imperialist body, and to downplay the Nuremberg trials.

[16] Fedun expressed opposition to working with the Polish Home Army, as well as the Romanian Iron Guard and other anti-communist insurgencies in Central and Eastern Europe.

(1948), and Why the USSR Must Be Rebuilt on the Principle of Independent National States (1950), would become hallmarks of ideological propaganda distributed to soldiers of the UPA at this time.

Who are the Banderites and What are They Fighting For?, published in both Russian and Ukrainian, served to encourage those loyal to the Soviet government or otherwise opposed to the UPA to reconsider their position.

According to the MGB's assessment, Fedun and Vasyl Okhrymovych [uk] were the leaders of the reformist faction, which was supported by the American Central Intelligence Agency.

A criminal case into Fedun began in 1949, overseen by the Ministry of State Security (MGB) and given the codename of Operation Jackal.

[7] In the autumn of 1951, by now dealing with direct attacks from MGB officers, Fedun travelled to Zhydachiv Raion, where he was placed under the guard of UPA commander Roman Kravchuk [uk].