why did the allies intervene the russian civil war 1918-1920?

Question

what were the reasons for them intervening? what did this lead to?

Answer 1

The allied forces intervened in the Russian Civil War in 1918, because the Communists wanted to pull Russia out of the Great War, and the Allies knew that would give the German forces many more divisions on the Western front. Sure enough, they came from the east and went onto the offensive in the west in March 1918.
Also, since most of Europe was still ruled by monarchies, surely the threat of a people's revolution overthrowing the monarchy in Russia was seen as a potential threat to the social order throughout Europe. This lead to Russia's isolation, the Comintern, the end of monarchies in many European countries, and indirectly, revolutions in Spain and China, Stalin and the Second World War.