Everyone knows about the Russian Civil War that unveiled the first powerful communist regimes of the world, but not too many had heard of the Allied Intervention in it, which speaks to an effort by Britain and Japan, along with several other conventionally named “imperialistic” powers, to militarily suppress the Red Army immediately after the termination of WWI. Even among the few well-informed, however, the participation of Chinese troops long remained an obscure image, and in-depth research on this topic is lacking. This brief paper seeks to enlighten readers on this matter by providing a chronology of events and an analysis of Chinese decisions, all aimed to answer one question: Why did China join the intervention?