Book excerpt: Lives of the Philadelphia Engineers examines the emergence of a new class of industrial entrepreneur and the world it confronted and shaped. Historians are reluctant to examine nineteenth-century American business leaders as a social group and this study helps remedy the defect. This book interweaves a history of the social and economic development of the largest centre of machine building in nineteenth-century America with the dramatic political narrative of sectional conflict, Civil War and Reconstruction. Crossing and re-crossing the boundary between industrial and political history, it throws new light on the process of industrialisation, the Civil War conflict, and the contested governance of nineteenth-century cities. While this study is firmly rooted in the experience of Philadelphia's machine builders, its historiographic significance extends to many of the important themes of mid-century American history. By rejecting the conventional viewpoint that timid manufacturers were conservative supporters of the plantation South and insisting that workshop owners rejected slavery, this study reinvigorates one of the Civil War's enduring interpretative battles. Of interest to scholars of business, economic, social, labour, education, urban and Civil War history, it will no doubt stimulate further debate and add a new angle to our understanding of nineteenth-century America.