
The poor SRs got war crimed by both sides of the civil war
For context, the Social Revolutionaries, a democratic socialist party in Russia, won the 1917 Constituent Assembly election before it was dissolved by Lenin's Bolsheviks. They were then persecuted as part of the Red Terror, which led to many joining the Whites. But as the war progressed, the anti-socialist Whites began to marginalize then purge the SRs.
https://en.wikipedia.org/wiki/1917_Russian_Constituent_Assembly_election