How the First Union Troops Entered Virginia at the Start of the Civil War

Virginia voted to secede from the Union on May 23, 1861. The first Union troops crossed the Potomac River into Alexandria County (today's Alexandria City and Arlington County) during the early morning hours of May 24, 1861. One officer reported that it was a beautiful moonlit night, and the moonbeams glittered brightly on the flashing muskets as the regiment silently advanced across the Long Bridge.

Eight Union regiments, under the command of Col. J.F.K. Mansfield, crossed the river and took up positions in Virginia. The first unit to cross was the 3rd U.S. Infantry under Maj. W. H. Wood. They moved via the Aqueduct Bridge (near the present Key Bridge) from Georgetown, then along the Georgetown Wagon Road (now Wilson Boulevard), and camped near present-day Clarendon.

The only opposition encountered came from a few Confederate pickets at the southern end of the Long Bridge and in Alexandria Harbor. There were no casualties. The Confederate volunteer units withdrew in good order.

Robert E. Lee's Arlington House, with Union soldiers out front, in 1864

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Arlington House—the recently vacated home of Robert E. Lee and his family—was occupied almost immediately. Gen. Charles W. Sandford of the 8th New York State Militia established his headquarters there.

By the time the first Union troops arrived in Alexandria County, many officials known to be Confederate sympathizers had already left. These included military and law enforcement officers, as well as the Clerk of Courts. Those who remained were either Union sympathizers or “quiet” Confederates.

On the night of June 1, 1861, Company E of the 1st Michigan Infantry was camped at Arlington Mill while on picket duty. Company G of the 11th New York Infantry, having come to relieve them, was stationed in a nearby house. Around 11:00 p.m., a squad of Virginia militiamen—reported by contemporary newspaper accounts to number only nine—approached the Union sentinels and camps and fired a volley. At least one newspaper account stated that, in the confusion, the Michigan men in the mill and the nearby Zouaves accidently fired on each other as well as at the Virginians. In any case, the Virginians were quickly driven off. The Union forces suffered one fatality: 21-year-old Henry S. Cornell of Company G.

Following the skirmish at Arlington Mills and the “battle” of Fairfax Court House on the same day, the Union Army made no further attempt to advance into Northern Virginia until June 17, when a reconnaissance in force encountered resistance at the nearby town of Vienna.

1865 map showing Fort Craig and nearby fortifications on the Arlington Lin

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Construction of the earliest fortifications in Arlington required about seven weeks—until mid-July 1861. Forts were thrown up right and left, trenches were cut through pastures and gardens, forests were cut down, and troop encampments were all about. According to Union Maj. Gen. J. G. Barnard, writing later, possession of property in Arlington was taken with little or no regard for the rights of owners or occupants.

At the time, Congress and much of the public believed the war would be short. Socialites and curious civilians even gathered for the first major battle—First Manassas (Bull Run)—on July 21, 1861. But Union forces were defeated and retreated toward Arlington, Alexandria, and Washington.

After the death and brutality of that July 21 battle, both North and South realized the war would not be short.

William Connery, the History Guy, is the author of  Civil War Northern Virginia 1861 and  Mosby's Raids in Civil War Northern Virginia.