As the title says, what would've happened if, rather than state socialism/communism, anarchism had become the dominant revolutionary left-wing ideology in 19th century Europe? Instead of Marx and Engels being the most notable figures on the far left, the ideas of people like Proudhon and Bakunin became more influential on would-be revolutionaries? How would this affect politics and economics in the 19th century? How would the Russian Revolution had turned out?