The Unio Trium Nationum (Latin for "Union of the Three Nations") was a pact of mutual aid codified in 1438 by three Estates of Transylvania: the (largely Hungarian) nobility, the Saxon (German) patrician class, and the free military Székelys. The union was directed against the whole of the peasantry, regardless of ethnicity, in response to the Transylvanian peasant revolt.