Jackson's operations against the B&O Railroad

Virginia Militia forces deploy and defend Harpers Ferry

After the Virginia Secession Convention reconvened and voted on April 17, provisionally, to secede, on the condition of a future ratification by a statewide referendum, the Governor of Virginia immediately began mobilizing the Virginia State Militia to strategic points around the state, including the assignment of Colonel Kenton Harper to Virginia's "Forces In and About Harper's Ferry, Virginia" on April 18.

Hours before Virginia Militia forces from Charlestown, West Virginia, and Winchester, Virginia, arrived on April 18, the Federal troops guarding the arsenal evacuated and burned it. Nine days later, on 27 April, Colonel Thomas J. (later "Stonewall") Jackson, then of the Virginia State Militia, was ordered to relieve Colonel Harper. He began the task of organizing the defense of Virginia at that location. During his first day commanding forces, on April 27, 1861, Colonel Jackson's men arrested one of the only four general officers in the regular army at that time, Brigadier General William Selby Harney, at Harpers Ferry, while he was taking a train to Washington, D.C. He was commanding the Department of the West, and was traveling from his headquarters in St. Louis, Missouri. Sometime following this, Colonel Jackson, while familiarizing himself with the B&O Railroad line, inspected Captain John D. Imboden's (later a CSA Brigadier General) assigned post, possessing the bridge across the Potomac River at Point of Rocks, Maryland.

Tensions build in May 1861

For the immediate time being, "B&O trains continued to run, with many interruptions and only with the consent of Virginia." Colonel Jackson realized that Harper's Ferry held not only important arms production factories, but was a choke-hold on the Baltimore and Ohio Railroad, the Chesapeake and Ohio Canal, and key telegraph trunk lines connecting Baltimore, Maryland and Washington, D.C. to the Ohio Valley and interior of the United States. As the war approached, the president of the B&O Railroad, John W. Garrett, who was sympathetic to the Union, became "outspoken" against the Confederacy, using "some strong adjectives to lend stress" to the word "rebel". Delagrange notes "As war seemed to be approaching, B&O President John Garrett tried to appear neutral (his sympathies were with the North), a good business practice because people weren't certain if Maryland would go Union or, even if it did, whether the line could be kept from the Confederates. Also, West Virginia had not separated from Virginia yet, so technically most of the B&O tracks lay in the South."

On May 5, 1861, Federal forces seized control of the B&O Relay House nine miles (14 km) west of Baltimore, so that Brigadier General B. F. Butler could "inspect and stop any further freight headed for military forces of Virginia." Butler was eager to assume authority in the absence of official instructions and finally occupied all of Baltimore on May 13, shortly before his promotion to Major General on May 16. He "started to arrest citizens known for their open Confederate support" including "Ross Winans, long-time inventor and locomotive builder." Political instability began to mount, as martial law was declared in Baltimore, which was a very secession-sympathetic city.