context: Friedrich Engels wrote The Peasant War in Germany , which opened up the issue of the early stages of German capitalism on later bourgeois "civil society" at the level of peasant economies. Engels' analysis was picked up in the middle 20th century by the French Annales School, and Marxist historians in East Germany and Britain. Using Karl Marx's concept of historical materialism,  Engels portrayed the events of 1524-1525 as prefiguring the 1848 Revolution. He wrote, "Three centuries have passed and many a thing has changed; still the Peasant War is not so impossibly far removed from our present struggle, and the opponents who have to be fought are essentially the same. We shall see the classes and fractions of classes which everywhere betrayed 1848 and 1849 in the role of traitors, though on a lower level of development, already in 1525." Engels ascribed the failure of the revolt to its fundamental conservatism. This led both Marx and Engels to conclude that the communist revolution, when it occurred, would be led not by a peasant army but by an urban proletariat.
question: Who did Engels say would lead the revolution?
answer: an urban proletariat