Act Zluky is signed, unifying the Ukrainian People's Republic and the West Ukrainian National Republic.

The Unification Act was an agreement signed by the Ukrainian People's Republic and the West Ukrainian People's Republic in Sophia Square in Kyiv on 22 January 1919. Since 1999, it is celebrated every year as the Day of Unity of Ukraine to commemorate the signing of the treaty; it is a state holiday in Ukraine, though not a public holiday.

The Ukrainian People's Republic (UPR) was a short-lived state in Eastern Europe. Prior to its proclamation, the Central Council of Ukraine was elected in March 1917 as a result of the February Revolution, and in June, it declared Ukrainian autonomy within Russia. Its autonomy was later recognized by the Russian Provisional Government. Following the October Revolution, the Central Council of Ukraine denounced the Bolshevik seizure of power and proclaimed the Ukrainian People's Republic with a territory including the area of approximately eight Russian imperial governorates. It formally declared its independence from Russia on 22 January 1918.

The West Ukrainian People's Republic was a short-lived state that controlled most of Eastern Galicia from November 1918 to July 1919. It included major cities of Lviv, Ternopil, Kolomyia, Drohobych, Boryslav, Stanyslaviv and right-bank Peremyshl. Apart from lands of Eastern Galicia, it also claimed the northern part of Bukovyna and the Carpathian Ruthenia. Politically, the Ukrainian National Democratic Party dominated the legislative assembly, guided by varying degrees of Greek Catholic, liberal and socialist ideology. Other parties represented included the Ukrainian Radical Party and the Christian Social Party.