Earl J. Hess 
Field Armies and Fortifications in the Civil War [PDF ebook] 
The Eastern Campaigns, 1861-1864

Earl J. Hess provides a narrative history of the use of fortifications–particularly trenches and other semi-permanent earthworks–used by Confederate and Union field armies at all major battle sites in the eastern theater of the Civil War. Hess moves beyond the technical aspects of construction to demonstrate the crucial role these earthworks played in the success or failure of field armies. A comprehensive study which draws on research and fieldwork from 300 battle sites, Field Armies and Fortifications in the Civil War is an indispensable reference for Civil War buffs and historians.