With grace and humility, Engels had assumed many a great labour after Marx died. This work is of inestimable value. And without the protracted efforts of the late Engels, Marxism at the opening of the twentieth century would not have been what it became, in its Kautskyan Second International form. The task of this article is to explore that “minor part” Engels played (without any illusion about the immense difficulty of the role) and with the full view that Engels’ life after Marx remained devoted to fighting for proletarian liberation.