In the topic of German-Slovak relationships and the war on the USSR in 1941–1945, the author capitalised the results of his long-term basic research of the relevant archival sources in the Military Historical Archive Bratislava, Slovak National Archive, State Archive Bratislava, Bundesarchiv-Militärarchiv Freiburg, Bundesarchiv Berlin, National Archive Prague, Archive of the Security Services Prague, Central Military Archive – Military Historical Archive Prague. This information was combined with the information gathered by studying professional literature. The author states that the German-Slovak relationships reflected the satellite relation of the Slovak Republic (SR) to Germany, whereas the representatives of the CS resistance gradually enforced the international recognition of the Czechoslovak Republic during 1940–1942. Engagement of the SR and its army in the war on USSR took place without major complications and the author states that the Slovak party even expressed initiative towards participating in the attack. The goal was to overtake Hungary and win the favour of Germany for the Vienna Arbitration review requirement. The Slovak party retained its initiative until the summer of 1942. However, since 1943, the Slovak Army command starts criticising the reprisals committed on the civilian population in the occupied USSR territory. In the face of decomposition of the army and loss of its fighting capacity, the Slovak party eventually managed to restrict the deployment of its units merely to the defensive construction works.