The aftermath of World War I saw the destruction of the Russian aristocracy. This occurred, of course, with the overthrow of the tsar and the Bolshevik Revolution. During the first wave of the Russian Revolution, peasants, operating largely independently of leaders in the cities, seized control of lands that belonged to old noble families. The old legal foundations of the aristocracy, which had been out of phase with social reality for some time (because nobles had come to own less and less of the land in the twentieth century,) were abolished.
Many Russian nobles fled the country in the wake of the Revolution, going to such locations as Great Britain and France. Many others joined the coalition that fought against the Bolsheviks and their allies in the Russian Civil War. Others, who numbered in the thousands, were executed by revolutionaries. But in general, with a very few exceptions, the Russian aristocracy saw themselves stripped of political, economic, and social status as a result of the revolution.
It should be noted that, while the Bolsheviks counted few aristocrats among their number, that many other reformers, including those who advocated abolishing the monarchy, were members of the aristocracy. It had been this faction of liberal aristocrats who led the Revolution of 1905, and many of them had been instrumental in the leadup to the first phase of the Revolution.