Could it be plausible for Serbia or Bulgaria or Turkey to become the 1st Marxist state in the world.
This is in the post-1900 forum, but you're welcome to suggest 19th century PoDs.
I bring up Serbia and Bulgaria, because I think they had Marxist Socialist parties before 1917, and because I think that successful external intervention to suppress such a revolution is not such a foregone conclusion here as it would be in so many other places.
I'll admit I have no specific PoD, and am lazily leaving that to others.
Here's my thinking:
If a Marxist revolution/takeover happens in Serbia or Bulgaria in the late 19th or early 20th century occurred, their geopolitical position could be such that potential interveners are more suspicious of each other than the radical revolutionaries, and they veto/deter each other's intervention allowing the revolutionaries to consolidate.
For instance, even if it's an avowedly atheist/socialist takeover, it will be "politically incorrect" for Europeans to support an Ottoman intervention against a historic Christian population.
In most times and places, Russia is also a bogeyman to Europe. Austria-Hungary and the Ottomans will always oppose its intervention and Britain will in early periods. By the time there is a Russo-British Entente that makes London tolerant of a Russian intervention, Germany will probably oppose Russian intervention.
The same applies in reverse in terms of the Russians objecting to an Austro-Hungarian intervention. Romania and Greece are too small to support regime changes on their own.
---As for Ottoman Turkey, I do not know if it even had a Marxist Socialist party. While I think external intervention and exploitation would be likely in the event of a radical Socialist revolution, I think it could easily result in amputation of fringe territories while in Anatolia and/or Thrace revolutionaries could remain in charge of a buffer state because external great powers don't trust each other intervening.
Thoughts?