This book presents the most accurate picture of the United States Marine Corps at the onset of the American Civil War and describes the actions of the Marines at the Battle of First Manassas, or as the Union called it, Bull Run. To tell the story of the actions of the U.S. Marines in the Manassas Campaign, distinguished Marine Corps historians Bruce H. Norton and Phillip Gibbons begin with Marine actions in October 1859 at Harpers Ferry, where they were instrumental in suppressing John Brown’s raid on the town’s Federal Armory and attempted slave insurrection. The Marines were the only professional fighting force that could respond immediately when the call for assistance came to retake the Armory, which Brown’s men had seized. The Marines were led by highly professional and well-trained officers and non-commissioned officers who represented a decades-old standard of excellence well established by the eve of the Civil War. The book then discusses Marine actions at the Battle of First Manassas, the Civil War’s first battle, on July 21, 1861, a story that has never been adequately or accurately told. In both engagements, the Marines proved that they were at all times ready, as the Corps remains to this very day.