At the 4th Congress of the RSDLP in 1906, a reunification was formally achieved. In contrast to the 2nd Congress, the Mensheviks were in the majority from start to finish, yet Martov's definition of a party member, which had prevailed at the 1st Congress, was replaced by Lenin's. On the other hand, numerous disagreements about alliances and strategy emerged. The two factions kept their separate structures and continued to operate separately.