Today marks the 161st anniversary of the first major battle of the Civil War

The Battle of First Manassas or First Bull Run as it was known in the North.

On Sunday, July 21, 1861, some 35,000 Union soldiers of the Army of Northeastern Virginia clashed with the combined Confederate Army of the Potomac and Army of the Valley (a force of near-equal strength). Irvin McDowell, the Federal commander, attempted to execute a wide flanking movement around the left end of the Confederate position that were entrenched along the banks of Bull Run. A force of some 15,000 men in two divisions were hampered by poor roads and poor discipline as they slowly made their way toward Sudley Ford. By the time they began crossing over Bull Run, it was well after daybreak and Confederate observers had spotted them, costing the Union flanking force the element of surprise.

A force of some 900 South Carolinians and Louisianans under Colonel Nathan "Shanks" Evans were the first to confront the Union hosts at the base of Matthews Hill. For 90 minutes the two sides engaged one another and the battle slowly grew larger as both sides pumped more men into the action. Overwhelming numbers finally took their toll on the Confederates. Evans, despite being reinforced by the brigades of Francis Bartow and Bernard Bee, broke under the pressure of the Union onslaught. The Confederates fell back to Henry Hill and a brief lull settled over the battlefield as both sides began to reform and reinforce.

The Union attacks resumed in the early afternoon against Henry Hill. Disjointed and poorly coordinated, the Confederate defenders managed to parry each blow that befell their positions atop the hill. At the center of the fight was a brigade of Virginians under the command of Brigadier General Thomas J. Jackson. While attempting to reform and rally his troops, Bernard Bee is said to have pointed at the mounted Jackson and exclaimed: "Look! There stands Jackson like a stonewall! Rally behind the Virginians!" A nickname and legend thus born, Jackson's brigade remained in the thick of the fight for the remainder of the afternoon.

The battle soon dissolved into control for the Union artillery batteries that had been moved precariously close to Confederate positions without adequate infantry support. The front moved back and forth across Henry Hill as both sides fought like hell for control of the cannon, with the Confederates eventually emerging victorious in the struggle.

With the battle hanging in the balance, a brigade of Confederates under the command of Richard Ewell broke through the Union right flank commanded by Oliver Howard. Like dominoes the Federal line began to collapse from right to left. Sensing victory within their grasp, Beauregard and Johnston - the two senior Confederates on the field - ordered an all out assault on the Union positions. It worked. The Federal army was soon in a full and orderly retreat back toward Bull Run.

Confederate artillery fire, however, soon turned that orderly retreat into a complete and total rout as thousands of Union soldiers broke and ran in every conceivable direction. Hundreds were captured by Confederate cavalry trailing behind the retreating columns of Yankees. Many did not stop running until they reached the safety of Washington, D.C.

The battle was over. In what was the bloodiest battle ever fought in the history of the United States to that point, the Union army suffered some 2,708 casualties (481 dead, 1,011 wounded, and 1,216 captured/missing). The Confederates also suffered heavily with 1,982 casualties (387 dead, 1,582 wounded, and just 13 captured/missing).

Within a matter of days, Irvin McDowell would be relieved of command and replaced by George B. McClellan. However, major fighting would not return to Virginia until the following spring.