With the outbreak of WWI (1914–1918), the participating countries began to promote separatist movements on their own territory, which aimed to destroy the foundations of hostile multinational empires. Of particular interest to the Russian authorities were the compatriots of the Slavic peoples of Austria-Hungary, who loudly declared their desire to destroy the Habsburg Empire. One of the most active diasporas was the Czechs, who managed to meet with Nicholas II twice in the first month of the war and achieve the formation of the Czech squad. However, the Czech question, initially incorporating the Slovak one due to the ethnic and linguistic proximity, exposed significant contradictions. An active part of the Slovak political elite living in Russia opposed the formation of a single Czech-Slovak state, because they were close to the idea of Slovakia’s accession to Russia. To popularize these ideas, a Slovak-Russian society named after L. Štur was established in Moscow. It received support from the outstanding Russians as well as the largest Slovak diasporas in the United States. The assistance of such important actors forced the Czechs to look for ways to resolve the conflict with the Slovaks, which undoubtedly led to the mainstreaming of the Slovak question. However, the cessions of 1915–1916 failed to resolve the conflict. Drawing on new archival sources and current historiography, the author concludes that the presence of multiple conflicts contributed to the formation of the Czech-Slovak national idea, which was free from asymmetry, and made Slovaks equal partners.