Origins of Czechoslovakia

That was the last time the two nations were united; the Hungarians had conquered Slovakia by the 11th century, but the Czechs maintained their own principality (a kingdom from 1198) of Bohemia from around 900 to 1918.

The Czechs and Slovaks were also formally united in 1436–1439, 1453–1457, and 1490–1918, when Hungary (which included Slovakia), Bohemia and other Central European states were ruled by the same kings.

At the end of the nineteenth century, the Czech and Slovak situations were very different because of their overlords' different stages of development within Austria-Hungary (the Austrians in Bohemia, the Hungarians in Slovakia).

The only common feature was Bohemia's status as the most industrialized part of Austria and Slovakia, albeit itself to different degrees: Around the start of the 20th century, the idea of a "Czecho-Slovak" entity began to be advocated by some Czech and Slovak leaders.

But although the Czech and Slovak national movements began drawing closer together, their ultimate goals remained unclear.

At least until World War I, the Czech and Slovak national movements struggled for autonomy within Austria and Hungary, respectively.

At the outbreak of World War I, the Czechs and Slovaks showed little enthusiasm for fighting for their perceived respective enemies, the Germans, the Austrians and the Hungarians, against fellow Slavs, the Russians and the Serbs.

Masaryk went to western Europe and began propagating the idea that the Austro-Hungarian Empire should be dismembered and that Czechoslovakia should be an independent state.

In 1916, together with Edvard Beneš and Milan Rastislav Štefánik, Masaryk created the Czechoslovak National Council.