The first part of the article concerns archive sources kept at the H. Hoover's Institute at the University of Stanford in California. Microfilms of these records were transferred to the Archive of New Records in Warsaw. Selected records from: Władysław Anders' Collection, the Embassy of the Polish Republic in Moscow and Kuibyshev covering the years 1941-1943, Ministry of Information and Documentation, and Stanisław Mikołajczyk's Papers served for a research recognition of the Red Army's auxiliaries calledOsoby Stroitielnyj Batalion("Stroibat"), as well as its other working divisions.Several dozen thousands of Poles and Polish citizens of different nationalities (born 1917-1920) were conscripted into these units. They came from these parts of Poland which were situated east of the Bug and the San rivers, the lands annexed to the Soviet Union in 1939.After establishing the Polish-Soviet diplomatic relations and the agreement of the 30thJuly 1941, the so-called amnesty for Poles, as well as after the August agreement on formation of the Polish Army under general Władysław Anders' command, the Polish Republic Embassy made an attempt to release these Poles from the Red Army and from its "stroibats". Despite the promise of Stalin himself they were never released and had to work for the army.The last part of the article presents documentation concerning endeavours of the Embassy and the Polish Army's command to release Poles from "stroibats" units and to introduce passports granting the Soviet Union citizenship until breaking diplomatic relations by the Soviet Union on the 26thApril 1943.