“We can distinctly hear firing again this afternoon in the direction of Harpers Ferry,” wrote a Union soldier in the Washington defenses on September 17, 1862. Closer to the Antietam battlefield, one onlooker attempted to count the number of Federal artillery rounds fired in one minute of action. He arrived at 78 shots per minute. Modern estimates guess the total number of artillery rounds fired during the Battle of Antietam as close to 50,000.
A good number of those rounds belched forth from the muzzles of the Army of the Potomac’s long-range guns—46 to be exact—posted on the bluffs east of Antietam Creek. For the Confederates on the other side of Antietam Creek, much of their line “was within range of the enemy’s rifle-guns…beyond the effective range of our guns,” said one Confederate artillerist. “Thence, perfectly safe themselves, they practised [sic] upon us at leisure all day.” The Union gunners used this advantage to such effect that by the end of September 17, they were basically out of ammunition, especially the thirty 20-lb. Parrott rifles that accompanied the army.
Even before the battle concluded, army commander George B. McClellan called on General-in-Chief Henry Halleck in Washington for more ammunition. “We are in the midst of the most terrible battle of the war,” McClellan told his superior after he asked for Halleck to militarily seize the Cumberland Valley Railroad so that ammunition and supplies could be sent to the front with haste. McClellan asked at 10 p.m. that night (September 17) if the United States Chief of Ordnance James Wolfe Ripley could send ammunition for his large Parrott rifles to Sharpsburg immediately.
While Ripley set about gathering the needed ammunition, the War Department began clearing the tracks for the impending train and its load. A presidential order, signed by Secretary of War Edwin Stanton, went out to the executives of the Northern Central Railroad, the Pennsylvania Central Railroad, and the Cumberland Valley Railroad. The train would be “run through at the fastest possible speed,” it said. “It must have the right of way throughout, as General McClellan needs the ammunition, to be used in the battle to be fought to-morrow [September 18].” By 1 a.m. on September 18, 2,500 rounds of 20-lb. Parrott ammunition—weighing in at 38 tons—was departing the Washington Arsenal bound for western Maryland.
Conveying this much tonnage of ammunition from Washington, DC to Sharpsburg, MD in such a short span of time required the crafty hand of many men, including Gen. Ripley, Pennsylvania Gov. Andrew Curtin, Edwin Stanton and his Assistant Secretary of War Peter Watson, John Garrett, President of the Baltimore and Ohio (B&O) Railroad, and a host of others. But in order to reach the Army of the Potomac in a timely manner, the ammunition-bearing train had to rely on several rail lines.
From Washington, DC, the long-range ammunition traveled on the Washington Branch of the B&O Railroad to Baltimore. At Baltimore, it hopped onto the Northern Central Railroad to just outside of Harrisburg, where the Cumberland Valley Railroad would carry the stores to Hagerstown, MD. By wagon, it was 70 miles from Washington to Sharpsburg. This route of connecting rail lines was approximately 200 miles long. However, it was the best the current circumstances allowed, as the B&O Railroad could get the ammunition no closer than Frederick.
The ammunition train consisted of a locomotive and its tender trailed by the four cars carrying the powder and shot for the Army of the Potomac. It was ready to begin its journey by 1 a.m. on September 18. This early part of the journey proved to be slow for unclear reasons; the train did not reach Baltimore until approximately 7 a.m. and it left the city on the Northern Central Railroad at 7:27 a.m. From Baltimore, the train hustled to Bridgeport, PA to connect to the Cumberland Valley Railroad. In this leg of the trip, it sped along at close to 30 miles per hour. Judge Watts now carried the load, which became heavier at Bridgeport thanks to an additional car of ammunition taken on from Harrisburg. At 12:42 p.m., Judge Watts chugged into Hagerstown, its destination. On average, the train ran at the breakneck speed of 37 miles per hour from Bridgeport to Hagerstown, though the exigencies of the moment demanded more and it often moved at 55 miles per hour.
Despite the slow start, the military takeover of the necessary railroads had worked. However, the Army of the Potomac and its guns still sat at least 14 miles away from Hagerstown’s railyard. While sources are scant on this part of the trip, time must be factored in to account for the 38 tons of ammunition bring offloaded from the train cars and loaded into wagons. Civil War wagon trains could move anywhere from 12 to 24 miles in one day, pending good road conditions. By the time the artillery ammunition likely reached the Antietam battlefield, darkness would have begun to set in (or already had), especially when one once again factors in the time it must have taken to unload and distribute the impressive tonnage of ordnance. The Army of the Potomac would have to wait until September 19 to use it but by then, their Confederate adversaries slipped back into Virginia.
Even though the ammunition did not arrive in time to be turned into shot and shell hurled towards the Confederate army on the west side of Antietam Creek, this lightning-fast transportation of ammunition in less than 12 hours over 200 miles of track marked an impressive achievement, to say the least. It showed the growing importance of the use of railroads in wartime, particularly as viable supply lines. One rider on the train recalled in 1892 of the episode, “Perhaps there is not another instance in the history of the world where ammunition has been moved such a distance with so much rapidity, and in the face of smoking and blazing journal boxes on the vehicles carrying it.”
 Lucius Shattuck to Mort, September 17, 1862, in Lucius L. Shattuck Letters, Bentley Historical Library.
 “Ammunition,” Central Press (Bellefonte, PA), October 17, 1862.
 Ezra A. Carman, The Maryland Campaign of September 1862, Vol. 2: Antietam, ed. by Thomas G. Clemens (El Dorado Hills, CA: Savas Beatie LLC, 2012), 355.
 Edward Porter Alexander, Military Memoirs of a Confederate: A Critical Narrative (New York: Da Capo Press, 1993), 246.
 OR, vol. 19, pt. 1, 206.
 OR, vol. 19, pt. 2, 312.
 Ibid., 313-14.
 Ibid., 322; “Ammunition,” Central Press (Bellefonte, PA), October 17, 1862.
 Isaac W. Heysinger, Antietam and the Maryland and Virginia Campaigns of 1862 (New York: The Neale Publishing Company, 1912), 146.
 William Bender Wilson, A Few Acts and Actors in the Tragedy of the Civil War in the United States (Philadelphia: William Bender Wilson, 1892), 73.
 Ibid.; “High-Speed Ammunition Run on the Cumberland Valley Railroad” interpretive marker, Cumberland Valley Rail Trail.
 Charles R. Shrader, “Field Logistics in the Civil War,” in Jay Luvaas and Harold W. Nelson, eds., The U.S. Army War College Guide to the Battle of Antietam (Carlisle, PA: South Mountain Press, Inc., 1987), 273. Sunset came at 6:06 p.m. on September 18, 1862, giving the ammunition only 5 hours and 24 minutes to be loaded off the trains, transported by wagon to the Antietam battlefield, unloaded and distributed before nightfall. Joseph L. Harsh, Sounding the Shallows: A Confederate Companion for the Maryland Campaign of 1862 (Kent, OH: The Kent State University Press, 2000), 20.
 Wilson, Acts and Actors, 74.