The revolutionary Vladimir Lenin had his suspicions about Stalin, one of his top lieutenants. “After taking over the position of General Secretary, comrade Stalin accumulated immeasurable power in his hands,” he wrote to the party congress in 1922 “and I am not certain whether he will be always able to use this power with the required care.” But by then it was already too late. Stalin used his appointment as the Secretary General, an administrative position, to place loyalists in key positions, so when the time for succession came, it did not matter than Lenin designated Trotsky, Stalin’s rival, for the post.

On this day, December 27, in 1927, at the 15th Congress of the All-Union Congress Party, Stalin’s bolsheviks consolidated their power. The last of the Trotskyite opposition was expelled, and Trotsky himself soon exiled.

After dispatching Trotsky, Stalin turned his attention to uniting the Politburo. Allying himself with one of the factions, he managed to marginalize and dismiss two more potential rivals, and then took care of his former allies by arguing they were impeding the progress of communism. Stalin set himself up as the logical successor to the founders of communism, Karl Marx and Friedrich Engels, and carefully weeded out the old-party Bolsheviks to instill his own brand of communism.