Why did the Croatian Sabor break relations with Austria-Hungary in 1918?

In October 1918, the Croatian Sabor voted to break relations with Austria-Hungary primarily due to the collapse of the Habsburg monarchy during World War I.1

This decision was driven by a convergence of critical factors:
* Political Instability: The Habsburg state was disintegrating, and there was widespread internal unrest, including a revolt among the peasantry.1
* External Military Pressure: Both Serbian and Italian armies were advancing toward Croatian territory, creating an urgent need for a new political arrangement to protect Croatian interests.1
* National Aspirations: There was a growing movement among South Slav politicians to solve Croatia's problems by establishing a unified South Slav state, moving away from the previous Hungarian-dominated political order.12

Following the break, the Sabor initially declared the unification of Croatia, Dalmatia, and Slavonia as an independent state before quickly moving to incorporate the region into a broader South Slav entity.1