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Army of the Potomac (CSA)

June 20, 1861 – June 1, 1862

Organized on June 20, 1861, the Army of the Potomac later became the Army of Northern Virginia, the principal military force of the Confederate States of America in the Eastern Theater of the American Civil War.

Following the election of Republican presidential candidate Abraham Lincoln on November 6, 1860, the United States began to unravel. On December 20, 1860, South Carolina became the first Southern state to ratify an ordinance of secession. By February 8, 1861, seven states had followed suit, and six of them had banded together to form the Provisional Confederate Government. Three weeks later, the newly-formed government established the Provisional Confederate Army, a volunteer force controlled by President Jefferson Davis. Although the Provisional Government later established a more permanent Confederate army, it never flourished, and the term "Confederate Army" became synonymous with the volunteer army.

As the Union dissolved, the seceding state governments began seizing Federal property within their borders, including forts and arsenals. Following Lincoln's inauguration on March 4, 1861, he resolved to bring a halt to the illegal occupation of federal facilities. Events reached a climax in early April when South Carolina Governor Francis Pickens demanded the evacuation of four federal strongholds in Charleston Harbor.When the Lincoln administration refused, Confederate forces began shelling the federal garrison at Fort Sumter on April 12, 1861, plunging the United States into civil war.

Three days after the fall of Fort Sumter, President Lincoln issued a proclamation calling for seventy-five thousand volunteers to suppress the Southern rebellion. Lincoln's appeal prompted four states from the upper South, including Virginia, to leave the Union. As both sides ramped up for war, Virginia Governor John Letcher appointed Robert E. Lee as commander of all of the state's military and naval forces on April 22, 1861. Virginia's proximity to Washington, DC assured that the Old Dominion would be the nexus of conflict. By early May, troops were pouring into the state from throughout the South. As Lee labored to organize the influx of recruits, he placed Philip St. George Cocke, brigadier-general of Virginia forces, in charge of all state troops along the Potomac River. On May 6, 1861, Lee instructed Cocke "to post at Manassas Gap Junction a force sufficient to defend that point against an attack likely to be made against it by troops from Washington." Cocke's defensive line would become known as the Alexandria Line.

On May 20, 1861, the Confederate Congress voted to move the capital of the Confederacy to Richmond, Virginia. Two days later, Virginia voters overwhelmingly ratified Virginia's ordinance of secession, paving the way for the state's incorporation into the Confederacy. As Virginia's forces were folded into the Provisional Confederate Army, Cocke was commissioned as a colonel in the newly organized Confederate forces in Virginia. Cocke's reduction in rank triggered his replacement as commander of the troops on the Alexandria Line. On May 21, 1861, Brigadier-General Milledge Luke Bonham temporarily superseded Cocke.

On May 31, 1861, Confederate President Jefferson Davis met with Brigadier-General P.G.T. Beauregard, hero of the occupation of Fort Sumter. The meeting took place at the new Confederate capital, which had moved from Montgomery, Alabama on the day before. No doubt intent on protecting the new capital, Davis informed Beauregard that he would replace Bonham as commander of the troops constructing defensive works along the Potomac River. After the meeting, Davis instructed Robert E. Lee to issue Special Orders, No. 149, on May 31, 1861, assigning Beauregard "to the command of the troops in the Alexandria line." Beauregard promptly traveled to Manassas Junction and relieved Bonham of his command on June 2, 1861. On June 20, 1861, Beauregard issued General Orders, No. 20, organizing troops under his command into six brigades that he referred to as the "First Corps, Army of the Potomac," marking the inception of the designation "Army of the Potomac."

On the opposite side of the Alexandria Line, President Lincoln and other federal officials were urging Brigadier-General Irvin McDowell, commander of the volunteer army amassing around Washington, to launch an offensive against the Confederate capital and to bring the rebellion to a swift end. Unsure of the readiness of his troops, McDowell reluctantly relented to political pressure and marched a force of nearly 35,000 soldiers (commonly, but not officially, known as the Army of Northeastern Virginia) out of Washington, toward Virginia on July 16, 1861.

Upon learning of McDowell's departure, Beauregard positioned approximately 22,000 soldiers, in a line along Bull Run, a stream near Manassas Junction. In anticipation of McDowell's offensive, the Confederate government made plans to rush Brigadier-General Joseph E. Johnston's Army of the Shenandoah by rail to Manassas to reinforce the Army of the Potomac. When Johnston arrived at Manassas, on July 20, 1861, Beauregard had already developed a battle plan for defeating McDowell's forces. Although Johnston was senior in rank to Beauregard, he deferred command of the forces in the field and approved Beauregard's plans for the impending Battle of Bull Run I.

On July 21, 1861, McDowell's forces attacked Beauregard's left flank. Initially, things went well for the Federals, as they drove the Confederates back from their defensive position. As the day wore on, however, reinforcements from Johnston's former Army of the Shenandoah arrived by rail, and the Union advance stalled. By late afternoon, the Confederates mounted a counterattack, driving the Union soldiers from the battlefield. The ensuing Federal retreat disintegrated into a rout, sending McDowell's troops scurrying back to Washington.

After the Confederate victory at the Battle of Bull Run I, Johnston assumed command of the combined armies, which retained the name "Army of the Potomac." Beauregard remained the de facto second in command, in charge of the 1st (and only) Corps. On September 25, 1861, Johnston issued General Orders, No. 31 (AOP/CSA) establishing the 2nd Corps of the Army of the Potomac under the command of Major General Gustavus W. Smith. Johnston directed that the troops of the 2nd Corps would "consist of the troops of this army not heretofore assigned to the First Corps," meaning the Army of the Shenandoah.

On October 22, 1861, Confederate Secretary of War Judah P. Benjamin issued General Orders, No. 15, announcing the establishment of the Department of Northern Virginia, commanded by Johnston. The new department was composed of three districts—the Potomac District, commanded by Beauregard, the Valley District, command by Major General Thomas J. Jackson, and the Aquia District, commanded by Major General Theophilus H. Holmes. Soon thereafter, Confederate officials began referring to the troops in the new department as the Army of Northern Virginia. Correspondence from the engineering bureau, dated February 25, 1862, referred to Johnston's forces as the Army of Northern Virginia. In a letter dated March 5, 1862, Robert E. Lee addressed Johnston as "Commanding, Army of Northern Virginia." By May, Johnston himself was referring to his command as the Army of Northern Virginia.

References to the Confederate Army of the Potomac ceased to occur after Johnston was seriously injured on May 31, 1862, during the Battle of Seven Pines (May 31-June 1, 1862). Confederate President Jefferson Davis appointed Lee, to replace Johnston in the field. On June 1, 1862, Lee issued Special Orders, No. 22, announcing that he was assuming command of Johnston's forces, which he referred to officially as the Army of Northern Virginia. From that date forward, the troops under Lee's command (including the Army of the Potomac) would forever be known as the Army of Northern Virginia.

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