The First World War provided a dramatic prologue to the formation of the Czechoslovak Republic in October 1918. As the end of the war approached, developments on the domestic political scene accelerated, although they did not proceed evenly across both halves of the Austro-Hungarian monarchy. In Austria, a certain amount of political relaxation had already occurred by 1917, while in Hungary government repression continued. A re-organised National Committee was active in the Czech Lands from as early as July 1918. In Slovakia, preparations to establish a Slovak National Council developed more slowly. The historic moment came on 30 October, when an assembly of representatives from the whole of Slovakia met at Turčiansky Svätý Martin, and elected a Slovak National Council that adopted the Declaration of the Slovak Nation. The council declared that only it, and not the Hungarian government or any other authority, was authorised to speak and act in the name of the Slovak branch of the Czechoslovak nation living within the Kingdom of Hungary. It also announced its support for future participation in all activities of the Czech nation.

On 28 October 1918, the National Committee in Prague declared the creation of an independent state of the Czechoslovak people, of which it formed the government. It also issued the First Act of the Czechoslovak State, decreeing the legal continuity of the new situation and subordinating all existing state and representative administrative authorities to it.