On July 21, 1861, at the First Battle of Bull Run, the first major engagement of the American Civil War, the Irish 69th New York Infantry Regiment fights under the green flag of Erin and the Stars and Stripes for the first time. The unit is in a brigade commanded by Col. William Tecumseh Sherman, whose name is now one of the most well-known of the war. He is not, however, well loved by the 69th New York.

The battle, called the Battle of First Manassas by the Confederate State Army, is fought in Prince William County, Virginia, just north of the city of Manassas and about thirty miles west-southwest of Washington, D.C. The Union Army is slow in positioning themselves, allowing Confederate reinforcements time to arrive by rail. Each side has about 18,000 poorly trained and poorly led troops. The Union army suffers an ignominious defeat that day, but the 69th is among a handful of Union regiments that perform well during the battle. Held in reserve at first, the 69th soon advances and routs the 4th Alabama. But when the brigade meets stiffer opposition, Sherman attacks with one regiment at a time, wasting his numbers. The battle is followed by a disorganized post-battle retreat of the Union forces.

Just months after the start of the war at Fort Sumter, the northern public clamors for a march against the Confederate capital of Richmond, Virginia, which is expected to bring an early end to the Confederacy. Yielding to political pressure, Brigadier General Irvin McDowell leads his unseasoned Union Army across Bull Run against the equally inexperienced Confederate Army of Brigadier General P. G. T. Beauregard, whose forces are camped near Manassas Junction. McDowell’s ambitious plan for a surprise flank attack on the Confederate left is poorly executed; nevertheless, the Confederates, who had been planning to attack the Union left flank, find themselves at an initial disadvantage.

Confederate reinforcements under Brigadier General Joseph E. Johnston arrive from the Shenandoah Valley by railroad, and the course of the battle quickly changes. A brigade of Virginians under a relatively unknown brigadier general from the Virginia Military Institute, Thomas J. Jackson, stands its ground, which results in Jackson receiving his famous nickname, “Stonewall.” The Confederates launch a strong counterattack, and as the Union troops begin withdrawing under fire, many panic and the retreat turns into a rout. McDowell’s men frantically run without order in the direction of Washington, D.C.

One of the last regiments off the field, the 69th loses 38 men that day, the first being Capt. James Haggerty from Donegal, and 59 wounded. Ninety-five are sent to Confederate prison camps, including its Sligo-born colonel, Michael Corcoran. One of the last men off the field is Waterford‘s Thomas Francis Meagher, captain of Company K, who eventually swims the last yards to safety across Bull Run creek. It is a rough beginning, but the regiment has begun a storied history that soon earns them the sobriquet “Fighting 69th.”

Both armies are sobered by the fierce fighting and the many casualties and realize that the war is going to be much longer and bloodier than anticipated. The First Battle of Bull Run highlights many of the problems and deficiencies that are typical of the first year of the war. Units are committed piecemeal, attacks are frontal, infantry fails to protect exposed artillery, tactical intelligence is minimal, and neither commander is able to employ his whole force effectively. McDowell, with 35,000 men, can commit only about 18,000, and the combined Confederate forces, with about 32,000 men, also commit 18,000.