This Althist tells what would have happened, if the Hungarian revolution in 1848-49 (and some other revolutions) succeed, and the Austrian Empire collapses.
Point of Divergence
The spring of 1848 called „Spirng of Nations”, because revolutions happened many cities across Europe from Paris to Pest-Buda. The Hungarian revolution was succesfull, and the Asutrian Empire had to give autonomy to the country. However, when Vienna repelled the rebellion, the government’s goal was annexing Hungary again. They set a rebellion in Croatia, and the croat army, led by Jellacic crossed the soutern borders of Hungary. The newly established government sent John Móga’s soldiers against the attackers.
The battle hapenned near Pákozd on 29th September 1848. The Hungarians won, Jellacic fled to Austria with his army. Móga chased him, but he stopped at the Austrian border on 10th October. In OTL he crossed the border only the end of the month. But ATL, he didn’t hesitate, and marched into enemy territory. In Vienna (like in OTL) another revolution broke out on 6th October, so Hungarian troops easily moved into the imperial capital, and they supported the revolution.
The Habsburg family was captured, and the rebels proclaimed the republic. A revolutional government was founded. The new republic made an alliance with Hungary, who also claimed the independence.
Meanwhile the Habsburg Empire started collapsing. Bohemia, Galicia and Italy declared independence. In the name of the Holy Alliance, Prussia joined the war and conquested Moravia and Eastern Bohemia. The Kingdom of Sradinia-Piedmont also declared war on the Austrian Republic and conquered Milan, Trent, Venice, and other Northern Italian Austrian claims. Dalmatia is attacked too, and the Sardinian armies captured the important cities and islands in the region.
The War of the Habsburg Collapsing ended in 1850 with the Peace of Berlin. The Holy Alliance and the Austrian Empire destroyed, Sardinia get Northern Italy and Dalmatia, Moravia and East Bohemia were annexed by the Prussians. But Hungary, Bohemia and Galicia became independent.
The revolutions were succesfull in Spain too. Andrew I, former general of the Spanish Army (only in ATL) started to reign as the King of Spain.