A Brief Summary of the Federal Military Use of the O&A Railroad 1861-1865
Immediately following Virginia's vote to withdraw from the Union in May 1861, Federal troops crossed the Potomac River and occupied the city and county of Alexandria. Possession was taken of all of the railroad facilities emanating out of the city. Although most of the rolling stock of the Orange and Alexandria had been removed before the invasion, the Federals took possession of the O&A's depot, shops, machinery and all property left behind including company records, rails of the Manassas Gap Railroad waiting to be delivered, and two locomotives ("Fairfax" and "Rapidan"). The machine shop, having been left intact, was immediately put to work repairing the locomotives and rolling stock and preparing the Iron work for several bridges that had been destroyed.
To facilitate movement of stores, a 1/4 mile connecting track was laid between the Alexandria, Loudoun & Hampshire and the O&A with the connection at the corner of Union and Queen Streets. In addition, a track was laid down Henry Street connecting the O&A and the Alexandria & Washington RR.
Upon reconnoitering westward down the O&A it was found that 1/4 mile of track had been removed and seven bridges destroyed between the city and Springfield Station, nine miles to the west. The rails were relaid and the bridges rebuilt. One bridge being a new Howe bridge and the rest being repaired with trestlework. A total of 5880 feet of bridging was constructed.
By November 1861 the O&A was being operated as far west as Springfield Station.
The United States Military Railroad is established in February 1862 within the Quartermaster Department.
In March 1862, the Confederates abandoned their position at Manassas Junction and retired to the south side of the Rappahannock River. The Federals immediately opened the O&A as far west as Manassas that same month. The line was reopened to Warrenton Junction in April and by July the Warrenton Branch Line had been opened. In August Union General John Pope advanced his Army of Virginia into Culpeper County and the US Military Railroad opened the O&A as far as the Rapidan River. This would be the furthest point the USMRR would use the line during the war.
In late August, Pope's army retreated back along the railroad to the north side of the Rappahannock River due to an advance of Lee's Army of Northern Virginia from Gordonsville. General 'Stonewall' Jackson took his Confederate Corps around Pope's flank and into his rear and cut the O&A at Bristoe Station and Manassas Junction. This forced Pope to abandon the Rappahannock Line. As the Confederate offensive continued, the O&A was abandoned back to Bull Run, and then with the final defeat of Pope at Second Manassas the entire line was abandoned with a loss of 7 locomotives and 295 cars.
The line remained abandoned until November when the Army of the Potomac returned from Maryland following the Battle at Sharpsburg (Antietam). The line was reopened to Bealeton and Warrenton in order to supply the army then moving into the Warrenton area. In November, Union General Ambrose Burnside ordered the army to march to Fredericksburg. The O&A remained open as far as Bull Run for the rest of the winter.
In April the USMRR opened the O&A to Bealeton to supply General Stoneman's Cavalry Corps and to support General Hooker's movement on Chancellorsville. Following Hooker's defeat at Chancellorsville, the line was again abandoned back to Bull Run. In June, a major Cavalry Battle at Brandy Station set the stage for both army's march north toward Pennsylvania. The O&A was utilized as a major supply source for the Union Army as it marched northward. Once the army moved across the Potomac, the entire line of the O&A was abandoned beyond the defenses of Washington. It remained abandoned until the return of the Army of the Potomac to the area following the Battle of Gettysburg. By the end of July the O&A was reopened to Culpeper.
In October, Lee once again took the offensive and forced the Federals to retire back to Centreville. Following the Battle at Bristoe Station, Lee retreated back south of the Rappahannock taking up 22 miles of track and destroying all the bridges between Broad Run and the Rappahannock. The USMRR Construction Corps repaired and opened the line to Warrenton Junction and Warrenton by October 30, and to Brandy Station and Culpeper by November 16. The Rappahannock River Bridge, 625 feet long and 35 feet high was erected in 19 working hours.
During the winter 1863-64, the rail line was further opened to Mitchell's Station south of Culpeper and became the primary supply line for the Army of the Potomac for the winter.
In May, 1864 the Army of the Potomac marched south out of Culpeper County to begin Grant's Overland Campaign. The O&A was abandoned by the USMRR back to Burke Station until September when orders were received to reopen the line to the Rappahannock. By October 2 the line was back in running order to the river, however that same day an order was received to abandon work on the O&A south of Manassas Junction and reopen the Manassas Gap Railroad. On October 10 a train was derailed near White Plains by Confederate guerrillas who removed a rail causing a train to fall down a steep embankment. M.J. McCrickett, Superintendent of the Railroad and 4 others were killed in the derailment. The MGRR was repaired as far as Piedmont by October 11.
On October 26 the MGRR was ordered abandoned and all the rails taken up from Piedmont back to Manassas Junction (34 miles). This was completed by November 10. The rails were transported to the Winchester & Potomac Railroad without change of cars and the rails relaid.
From November 1864 until June 27, 1865 the O&A was operated only as far as Fairfax Station. One regular train was operated each way per day and two quartermaster wood trains were run daily.
On June 27, 1865 the USMRR turned over the Orange & Alexandria Railroad to designated agents of the Board of Public Works of Virginia.