The pulsating armed conflict in the Donbas (periodically "frozen") since 2014 has highlighted the real intentions of the Russian Federation: to prevent the disintegration of the Russian-Ukrainian monolith in geopolitical, economic, technological and cultural issues. The revived Russian military-bureaucratic imperialism used the well-known method of "gathering Ruthenian lands", practiced since the 14th century. According to the Kremlin, Donbas is of special value, despite the war damage, it is still a critical resource, technological and industrial center (including the great potential of the arms industry) and research and development. Therefore, on February 20, 2022, the Ukrainian-Russian war broke out under the banner of the so-called "Special Military Operation". The Russian-Ukrainian war changed the face of both Europe and the world forever. Russian neo-imperialism led to open aggression against another European state - Ukraine, which borders Poland. In connection with the functioning of the Territorial Defense Forces of Ukraine, conclusions must be drawn for the Polish Territorial Defense Forces from the first stage of the war in Ukraine. So what is the genesis of the Ukrainian-Russian war? How were the Ukrainian Territorial Defense Forces (Territorial Defense Forces) shaped? How were the Polish Territorial Defense Forces shaped? What is the function and tasks of the Ukrainian Territorial Defense Forces? What is the role of the Ukrainian Territorial Defense Forces in relation to the Ukrainian Land Forces? What is the function and tasks of the Polish Territorial Defense Forces? What is the role of the Polish Territorial Defense Forces in relation to the Land Forces? How is the Ukrainian WOT model different from the Polish one? What conclusions can be drawn from the first stage of the war in Ukraine? The subject of the analysis will be the cause of the Ukrainian-Russian conflict, the history of the formation of the Polish and Ukrainian Territorial Defense Forces and the functioning of these formations in the first stage of the war. The aim of this study is to synthesize the genesis of the Russian-Ukrainian conflict, and the conditions for the formation of the Territorial Defense Forces in Ukraine and Poland. A comparative analysis of two models in terms of functional-task as well as structural-organizational and conclusions for the Polish Territorial Defense Forces in the context of the experiences of the first months of the war in Ukraine.