This paper presents the process of building an independent Polish state during the First World War, which, from the Polish perspective, was the most important result of this conflict. The article focuses mainly on the political and military developments in the Polish territories between 1914 and 1921. These include the internationalization of the Polish question, Polish political and military activity, occupation regimes in the Polish territories, the collapse of foreign authorities in Poland, the establishment of Polish political institutions, and Polish social and cultural life.