Along with Karl Marx, his friend and frequent co-author, Engels is a towering figure in the development of Marxist theory. Born in the German city of Barmen in 1820, his family were wealthy factory owners, an ironic beginning for someone who would later dedicate his life to the abolition of capitalism. Like many leading socialists of the 19th century, he traveled extensively across Europe, deepening his understanding of a class system that maintained the privileges of the few at the expense of the many. Working for a family business in Manchester, England, he met Mary Burns, an Irish woman from the working class who helped introduce him to the deplorable conditions of life in the heartland of the Industrial Revolution. The two were partners until Burns’s death in 1863, although they never married and Engels also pursued other sexual partners (it is unknown if Burns did the same).

On a trip through Paris, Engels met Karl Marx, and they quickly became collaborators in both writing and political organization, joining an underground Communist group called The League of the Just. Engels then moved to Belgium, a haven for political dissidents, and in early 1848 he and Marx coauthored the Manifesto of the Communist Party, a clarion call to revolution which they issued shortly before the outbreak of anti-monarchical revolutions throughout Europe.