Civil War Breaks Out
At 4:30 a.m., April 12, 1861, Confederate forces began shelling the federal garrison at Fort Sumter, South Carolina, plunging the United States into the American Civil War. Three days later, President Abraham Lincoln issued a proclamation calling for 75,000 volunteers to suppress the Southern rebellion. On April 25, the first of what would eventually amount to thousands of raw recruits began streaming into Washington, DC. The rapid buildup of local regiments required the United States War Department to create structure out of chaos quickly. By late April, the War Department began organizing the volunteer army into military districts.
Organization of the Army
On May 27, 1861, the War Department issued General Orders No. 20, stating that “All that part of Virginia, east of the Allegheny Mountains and north of James river, except Fort Monroe and sixty miles around the same, will, for the present, constitute a new Military Geographical Department, under the command of Brigadier Gen. Irvin McDowell, U. S. A., whose headquarters will be movable.” Official documents subsequently referred to the “new Military Geographical Department” as the Department of Northeastern Virginia.
McDowell had under his command approximately 30,000 to 35,000 raw recruits, many of whom had enlisted for just three months. He divided force into five divisions led by:
- Brigadier-General Daniel Tyler
- Colonel David Hunter
- Colonel Samuel Heintzelman
- Brigadier-General Theodore Runyon
- Colonel D. S. Miles
Many historical sources refer to McDowell’s force as the Army of Northeastern Virginia, but there is scant evidence to support the designation as official.
First Battle of Bull Run
After taking command on May 28, 1861, McDowell focused his efforts over the next few weeks on organizing and training his green troops. President Lincoln and other government officials, however, were less concerned about the army’s lack of seasoning. Eager for a quick end to the rebellion, they pressured McDowell for action, sooner rather than later. Despite his misgivings, McDowell gave in to political pressure and marched his soldiers out of Washington, toward Manassas, Virginia, on July 16, 1861. On July 21 the Confederate Army of the Potomac, reinforced by the Army of the Shenandoah, routed the Army of Northeastern Virginia at the First Battle of Bull Run, sending them scurrying back to the Union defenses near Washington in a disorganized retreat.
Dissolution of the Army
One week after the embarrassing defeat, the federal government began reorganizing its forces near the nation’s capital. On July 25, 1861, the War Department issued General Orders, No. 47, merging the Department of Northeastern Virginia with the Department of Washington to create the Division of the Potomac commanded by Major General George B. McClellan.
Three weeks later, on August 17, Lieutenant General Winfield Scott issued General Orders, No.15 (Headquarters of the Army) announcing a further consolidation and the creation of the Department of the Potomac, again commanded by. McClellan. On August 20, McClellan issued General Orders No. 1 (Army of the Potomac), assuming “command of the Army of the Potomac, comprising the troops serving in the former departments of Washington and Northeastern Virginia, in the Valley of the Shenandoah, and in the States of Maryland and Delaware.” The troops who served under McDowell formed the nucleus of the Army of the Potomac.