The Hungarian Civil War (German: Ungarische Bürgerkrieg, Hungarian: magyar polgárháború) was fought between the pro Habsburg forces and its nationalists allies and Hungary, on the Eastern part of Austria-Hungary. The civil conflict started of the refusal of Hungarians delegates to divide lands of the Crown of Saint Stephen (Kingdom of Hungary) and give full autonomy to Croatia, Transylvania and other nationalities.
After the end of the Hungarian Civil War and during World War I the Federal Solution (Föderale Lösung/Szövetségi megoldás) of 1917 was negotiated creating the Federal State of Austria-Hungary. It was fully implemented in 1920.
In right wing nationalist circles it is called the Hungarian Uprising of 1915.