Edited per /u/commiespaceinvader's reply.

It's odd that so many sources go into excruciating detail about the start of a war, but don't mention the details of the end.

The immediate collapse of Austria-Hungary was pretty calm.

In an attempt to appease the Allies, Emperor Karl on 6 October 1918 issued a Manifesto giving self-government for the minorities in the Austrian half of the empire. This was an attempt to preserve at least some form of union. It succeeded about as well as the new Union treaty and Commonwealth of Independent States at the end of the Soviet Union, which is to say, it detonated the ammunition magazine. The committee to set it up was rejected by every ethnic group, whether by boycott, walkout, rejection, or lack of participation. It was seen as an admission of defeat. And the estates set up were pretty much parliaments for the successor states.

And the Allies smelled blood. Wilson's Fourteen Points had just said "the freest opportunity of autonomous development" for minorities, but now he demanded independence for Czechoslovakia and the South Slavs.

Emperor Karl is recorded as saying "My only wish is that everything shall be liquidated peaceably", and what he had control of (the start) was pretty peaceful.

Czechs like Masaryk had already declared independence and been recognized as co-belligerents by the Allies. The Prague National Committee took over administration on 28 October. The Imperial government simply left. The Slovak National Council announced union on 30 October, though full Slovak union didn't happen until the Magyars were driven out in 1920.

The National Council of Serbs, Crats, and Slovenes was set up on 6 October, and the governor of Croatia, upon orders from Emperor Karl, handed over executive power on 29 October. The Council declared union with Serbia, and Yugoslavia was declared on 4 December.

Poles had been the "model minority", after the three-way partition hating Germany and Russia for their oppressions, but not Austria. But opinions changed late, after the Russian Revolution. The Polish National Committee in Paris pushed for Allied help. At the end of October, Austrian troops started withdrawing from Galicia.

The other minorities eventually left too: Transylvania to Romania, Italian territories to Italy.

The centers, Austria and Hungary, still held on ... until the Hungarian parliament called back its troops in late October, and on 26 October Hungarian troops at the front announced that they were going home, and were allowed to. Karoli established a Hungarian National Council, with its first demand separation from Austria. Karl appointed him Prime Minister on 31 October.

Austrian troops followed suit to go home. And somehow Austrians discovered nationalism and ethnic unity. The Reichsrat designated themselves the Provisional National Assembly of the Independent German-Austrian State. They elected ministers, but didn't yet depose the Emperor or his government, so both sets of ministers sat together for three weeks, with the new ministers learning from the old.

But with troops fleeing back, war workers hungry and roaming, prisoner of war camps around Vienna breaking down ... mobs ranged in Vienna. And then on 10 November was Kaiser Wilhelm's flight and socialist government in Germany. Ministers on 11 November begged Karl to abdicate. He didn't technically, but he did sign a declaration with "I renounce my share in the affairs of state" and felt his family had to leave Vienna the next day. The same sort of renunciation he signed with respect to Hungary on 13 November.

Austria's basic law proclaimed "German Austria is an integral part of the German Republic", but the Allies didn't allow that, so Austria stumbled slowly into national status.

Sounds nice and calm? That was just the start ...