The union of Hungary and Romania comprises proposed unsuccessful 20th-century, mostly interbellum, attempts to unite the Kingdom or Republic of Hungary with the Kingdom of Romania.
Such proposals were most active in 1919 and 1920, though they had appeared somewhat earlier and continued up to World War II.
[1][2][3] The proposed union would have been ruled by the Romanian Hohenzollern-Sigmaringen dynasty.
The project saw support and opposition on both the Romanian and Hungarian sides.
[2] Hungary's reasons to favor the proposed union were prevention of Hungary's political isolation and Hungarian hopes for getting back Transylvania, or at least securing autonomy for Transylvania's Hungarian minority.