Lenin was unknown at the time And so was Souvarine Lenin didn t knew him and even didn t knew that Souvarine had to fight in WWI from 1914 to 1916 his brother died at war that year The sentence has to be changed and if not deleted I agree that the dispute is obscure that s a problem You wrote He became associated with Totsky s Left Opposition It s not true either For reference if you can read french see the book by Jean Louis Pann or even better the work by Charles Jacquier