In 1861, Union Mill Road was a dirt wagon track used primarily by local farmers. It ran south from Braddock road, and after meandering through the countryside on the east side of Little Rocky Run for nearly four miles, it crossed the Orange and Alexandria railroad tracks.
Situated next to the road and tracks was Union Mills Station, one of the original stops on the railroad line. Located near Popes Head Creek close to its confluence with Bull Run, Union Mills was, along with Sangster, Fairfax and Burke, among the first stations opened when the Orange and Alexandria Railroad began operation in the early 1850s. This far-reaching new form of transportation technology helped expand the markets for the region's farm products and drastically reduced transportation and travel costs. The railroad brought increased prosperity and improved the quality of life for the people in Northern Virginia even though train wrecks at the unheard of speed of 25 miles per hour rapidly became a major cause of accidental death.
When the Civil War began, the railroad was suddenly transformed from being a benign mover of civilian freight and passengers into a military implement of war. Almost overnight, its benefits changed into hardships for those who lived near the tracks. Union Mills was no longer a quiet country station; it became a place with a high degree of military significance. It was so important that U.S. President Abraham Lincoln and Confederate President Jefferson Davis knew all about Union Mills. Generals such as Joseph E. Johnston, Robert E. Lee, Stonewall Jackson, John Pope, George Meade and thousands of the soldiers who served with them also became familiar with the location. During the first year of the war, the Confederates made the Union Mills area part of the defense line that ran from Centreville to Manassas Junction. After the Confederates departed in early 1862, Federal troops were stationed at Union Mills to protect the Bull Run railroad bridge (destroyed and rebuilt seven times during the war) and they expanded the fortifications and constructed a number of new ones. As the armies marched and countermarched along the railroad line, the defenses were further modified as they changed hands.
As the war got underway, it became clear to President Lincoln and his advisors that it was going to be impossible to guard long stretches of track against attack by Confederate raiders. If the rail lines could not be protected from damage, they would have to be repaired and returned to service in the shortest time possible. In April 1862, Herman Haupt, a railroad construction genius who had a reputation for getting things done, was called to Washington by the Lincoln administration and asked to fix the vexing problem. Haupt was appointed to the position of Chief of Construction and Transportation of the newly established U.S. Military Railroad (USMR), an organization responsible for all railroad operations on captured Confederate tracks.
As Haupt went to work, it was at places such as Union Mills that his highly organized and specialized repair crews honed their skills as they struggled to keep the Orange and Alexandria line functioning. The rapid repair procedures Haupt developed to replace bridges, track and just about everything else involved in keeping a railroad operating allowed the USMR to keep vital rail supply lines functioning.
The USMR established a base of operations at Union Mills. It was a facility to service equipment and store replacement parts for railroad rolling stock, water tanks, prefabricated bridges, ties and rails. The knowledge USMR crews gained in Northern Virginia proved to be an invaluable logistical asset to Lincoln's war effort. As new techniques were developed and tested, the information was passed along to the other locations where the USMR operated trains. During the later years of the war, Gen. Sherman's Union army drove into Georgia utilizing a sophisticated rail supply network that could be repaired almost as fast as Rebel raiders could wreck it.
Down the tracks west of Union Mills, the Union army established a massive quartermaster depot at Manassas Junction. By the late summer of 1862, the sprawling depot covered nearly a square mile, its warehouses crammed with military supplies of every description. On the depot's two spur railroad sidings, each a half mile long, were parked more than 100 box cars. When the telegraph line to Washington suddenly went dead in late August 1862, Union commanders had no way to know that it was Gen. Stonewall Jackson's 23,000 man army corps that had suddenly emerged out of nowhere and pounced on the supply base. Thinking that it was no more than an annoying cavalry raid, they rushed a brigade of New Jersey troops by rail to the vicinity of Union Mills with the objective of holding the bridge and possibly driving away the raiders. Having no idea of what they were getting into, the unseasoned and eager troops disembarked from the trains and marched west. When they ran into Jackson's veterans they were routed, their commander and approximately 135 others killed or wounded and another 200 captured. The panicked survivors fled eastward, abandoning the bridge and bringing with them the shocking news that there was more than Rebel cavalry at the supply depot.
To prevent another rude interruption of the depot's looting and to disrupt rail traffic, Jackson ordered the bridge destroyed. When the Confederates pulled out during the night of Aug. 27, 1862, they left behind them a sky reddened by burning warehouses, rail cars and exploding ammunition dumps. The great Union supply depot had been obliterated, never again to be rebuilt. Haupt's crews went to work and reconstructed the Bull Run railroad bridge, only to see it quickly lost again after the Union army retreated into Washington in early September following the battle of Second Manassas.
On Oct. 15, 1863, Gen. George Meade, located at his headquarters in Centreville, notified the War Department in Washington that "Generals Warren and Sykes were successfully withdrawn last night, and the army is now at Union Mills, Centreville, Chantilly, and Fairfax Court House, awaiting the movements of the enemy." Union Mills was the southern anchor of a strong Federal defensive position that stretched through Centreville to Frying Pan Church. The VI Corps held the line between Frying Pan Church and Chantilly. The II Corps occupied the section between Chantilly and Centreville. The I and III Corps controlled the ground south of Centreville to Union Mills. The V Corps, in reserve, oscillated between Centreville and Fairfax Court House, marching back and forth four times in four days while its weary soldiers tried to figure out what the generals were trying to accomplish with all the useless movement.
Knowing that Gen. Meade had 80,000 men in his battle line, President Lincoln wrote to him on Oct. 16, 1863, strongly suggesting that Meade launch an attack against Lee's forces. The President told the general that he would personally take the blame if the attack failed. We will never know if Gen. Meade intended to take President Lincoln's advice because Lee's army began to withdraw on its own accord on Oct. 17. As the Union army moved slowly in pursuit through the chilly early autumn mud, the repair gangs began the work of rebuilding the destroyed Orange and Alexandria right of way.
A new stop named Devereux Station was established on the railroad line less than two miles east of Union Mills during the war. It began as a place to load and ship the wood burned in steam locomotives and the timber needed for military construction projects. The station's name was changed to Clifton in the late 1860s. After the war ended, Union Mills faded from the maps, its civilian functions most likely absorbed by the new station at Clifton. With the control and repair of the railroad line no longer a military necessity, Union Mills had lost its last reason for existence. The modern railroad follows the route of the old Orange and Alexandria line. The abutments of the Civil War era bridge still stand like lonely sentinels next to current railroad bridge over Bull Run. The stretch of shiny track running west out of Clifton is a reminder of the time Herman Haupt and his repair crews helped make military history and Union Mills was a location of real consequence.