The Rusyn-Ukrainian autonomous region of eastern Czecho-Slovakia under Avgustyn Voloshyn, renamed Carpatho-Ukraine on 30 December 1938; as Germany dismembered the state on 15 March 1939 it proclaimed independence from Khust — a republic that lasted a single day.
Invaded by Hungary on 14-18 March 1939 and annexed after its one-day independence; the region remained Hungarian until the Red Army arrived in 1944, was ceded to the Soviet Union in June 1945, and is today Ukraine's Zakarpattia Oblast.
Polity-specific history by a man who served in the Voloshyn government — the autonomy, the one-day republic, and the Hungarian occupation. (Open Library verified: Vincent Shandor, 1997)
The standard regional history of Carpathian Rus, placing the 1938-39 autonomy and independence episode in the longer Rusyn story. (Open Library verified: Paul R. Magocsi, 2015)