The article covers the issues of formation, reorganization, and combat operations of the Ukrainian People’s Republic Army together with the troops of the Republic of Poland (April–October 1920) in the view of the modern Ukrainian historiography. It is noted that in their works, modern Ukrainian historians pay much attention to the hopeless situation in which the UPR found itself in late 1919 after a grueling struggle with the enemies of the Ukrainian statehood “in the death quadrant”. The achievements of modern Ukrainian scholars are analyzed, which consider the causes and consequences of the Warsaw Pact between the leaders of Poland and the UPR J. Pilsudski and S. Petliura, and focus on the diversity of opinions and judgments of domestic researchers about this page of the Ukrainian history. The article considers the works of Ukrainian scholars which cover the practical implementation of the Warsaw Pacts during the joint hostilities of Polish and Ukrainian troops in the above mentioned period, and focuses on the successes and failures of this military campaign. It notes that the disinterest in strengthening the Ukrainian Army, demonstrated by the Polish government after the armistice of Poland with the Soviet Russia on October 12, 1920, as the former was almost entirely dependent on Polish aid in the military and economic spheres, nullified the independent combat activities of the UPR Army and ended with a failed strategic goal – preservation of the Ukrainian statehood, which led to the internment of Ukrainian soldiers on November 21, 1920 in the Polish territory.