Czechoslovakia (1918–1992)

Czech and Slovak Federative Republic

Carved from Austria-Hungary in 1918, Czechoslovakia survived occupation and communism only to split peacefully on 1 January 1993 — the Czech Republic and Slovakia parted without a single shot.

The split was so amicable it's remembered as the Velvet Divorce — no referendum was ever held, and the Czechs quietly kept the old flag.