Book excerpt: "Hess studies the use of fortifications by tracing the campaigns of the Army of the Potomac and the Army of Northern Virginia from April 1861 to April 1864. He considers the role of field fortifications in the defense of cities, river crossings, and railroads and in numerous battles. Blending technical aspects of construction with operational history, Hess demonstrates the crucial role these earthworks played in the success or failure of field armies." "Based on fieldwork at 300 battle sites and extensive research in official reports, letters, diaries, and archaeological studies, this book stands to become an indispensable reference for Civil War historians."--BOOK JACKET.