Which preposition to use with bolsheviki

at Occurrences 1%

March 2Treaty of peace with Germany signed by Bolsheviki at Brest-Litovsk.

in Occurrences 1%

BOLSHEVIKI EXECUTE EX-CZAR Former Czar Nicholas of Russia was executed by the Bolsheviki in July, 1918, having been held as a prisoner since his dethronement.

Which preposition to use with  bolsheviki