A controversial character largely known (as depicted in the movie Glory) as a Union colonel who led Black soldiers in the Civil War, James Montgomery (1814–71) waged a far more personal and radical war against slavery than popular history suggests. It is the true story of this militant abolitionist that Todd Mildfelt and David D. Schafer tell in Abolitionist of the Most Dangerous Kind, summoning a life fiercely lived in struggle against the expansion of slavery into the West and during the Civil War. This book follows a harrowing path through the turbulent world of the 1850s and 1860s as Montgomery, with the fervor of an Old Testament prophet, inflicts destructive retribution on Southern slaveholders wherever he finds them, crossing paths with notable abolitionists John Brown and Harriet Tubman along the way. During the tumultuous years of “Bleeding Kansas,” he became a guerilla chieftain of the antislavery vigilantes known as Jayhawkers. When the war broke out in 1861, Montgomery led a regiment of white troops who helped hundreds of enslaved people in Missouri reach freedom in Kansas. Drawing on regimental records in the National Archives, the authors provide new insights into the experiences of African American men who served in Montgomery’s next regiment, the Thirty-Fourth United States Colored Troops (formerly Second South Carolina Infantry). Montgomery helped enslaved men and women escape via one of the least-explored underground railways in the nation, from Arkansas and Missouri through Kansas and Nebraska. With support of abolitionists in Massachusetts, he spearheaded resistance to the Fugitive Slave Act in Kansas. And, when war came, he led Black soldiers in striking at the very heart of the Confederacy. His full story thus illuminates the actions of both militant abolitionists and the enslaved people fighting to destroy the peculiar institution.