Monumental and revelatory, Free Labor explores labor activism throughout the country during a period of incredible diversity and fluidity: the American Civil War. Mark A. Lause describes how the working class radicalized during the war as a response to economic crisis, the political opportunity created by the election of Abraham Lincoln, and the ideology of free labor and abolition. His account moves from battlefield and picket line to the negotiating table, as he discusses how leaders and the rank-and-file alike adapted tactics and modes of operation to specific circumstances. His close attention to women and African Americans, meanwhile, dismantles notions of the working class as synonymous with whiteness and maleness.

In addition, Lause offers a nuanced consideration of race's role in the politics of national labor organizations, in segregated industries in the border North and South, and in black resistance in the secessionist South, creatively reading self-emancipation as the largest general strike in U.S. history.