Williams has culled a vast amount of primary-source material, much of it never before published, to shed new light on Custer's forces and provide previously unknown names for several troopers. As a reference for future historians, the book includes for the first time the 400-plus pension-file and personal-file numbers for Custer's troops. The volume also offers new information on Custer himself and on the civilian mule-packers and American Indian scouts who accompanied the expedition.
As the first in-depth analysis of the statistics related to the battle, Military Register of Custer's Last Command is the most extensive work available on the 7th Cavalry. With its exhaustive bibliography, it will stand as a definitive resource for historians and enthusiasts and a tribute to all enlisted soldiers on the western frontier.