Robert Lewis Dabney was an American Christian theologian and a Southern Presbyterian pastor, but he's best known for being chief of staff for General Thomas Jonathan "Stonewall" Jackson during his famous Valley Campaign and the Seven Days Battles.
Jackson was one of the most famous generals of the Civil War, and one of the most successful for the Confederates. Jackson got his famous nickname during the First Battle of Bull Run, when another Confederate general told his men to rally behind Jackson's brigade. After being the hero at Bull Run, Jackson led an army in the Valley Campaign of 1862, fighting three Union armies and keeping them from linking together.
Jackson also participated at Second Bull Run, Antietam and Fredericksburg, but his most famous battle was Chancellorsville, when he marched his men on a famous flank march and attack at Chancellorsville on May 2, 1863. The march would end up winning the battle for the Confederates, but Jackson was mortally wounded that night.
Dabney's biography of Jackson is invaluable to all Civil War students, not only for the history but as a piece of Lost Cause literature.