Lincoln's Cavalrymen describes the organizational, administrative, and operational history of the mounted arm of ""Mr. Lincoln's Army."" Historian Edward G. Longacre consulted at least fifty manuscript collections pertaining to general officers of cavalry, as well as the unpublished letters and diaries of more than 450 officers and enlisted men, representing almost every mounted unit in the Army of the Potomac.

The result is the most comprehensive history of the Union cavalry to date. It covers the gamut of cavalry life - not only field operations but also the recruiting, organizing, mounting, remounting, equipping, training, tactical instruction, and war-long support of this critical branch of the nineteenthcentury army. The book vividly portrays the cavalry's most influential commanders and assesses the depth and quality of its leadership. Longacre also seeks to place the cavalry in the context of the army and the war effort as a whole.