Keedysville in Washington County, Maryland — The American Northeast (Mid-Atlantic)
Army Headquarters
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Signal Station
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Field Hospital
Antietam National Battlefield
| | National Park Service, U.S. Department of the Interior | |

Photographed by Devry Becker Jones (CC0), April 1, 2025
1. Army Headquarters / Signal Station / Field Hospital Marker
Army Headquarters
Gen. George McClellan used the Pry House as the headquarters for the Union Army of the Potomac. The officers brought some of the Pry furniture out on the lawn where eyewitnesses described a "small redan built of fence rails" with telescopes mounted, and how the commander "stood in a soldierly attitude intently watching the battle." Reporter Charles Coffin wrote how he rode to "the large square mansion of Mr. Pry" where "the general was sitting in an arm chair his staff were about him, their horses saddled and bridled, were hitched to the trees and fences." When President Lincoln visited in October, Gen. McClellan brought him to the Pry House to see the headquarters site.
Signal Station
Positioned on high ground, using flags or torches waving back and forth to talk to each other, both armies used this new signal technology that permitted rapid communication across the battlefield. With signal stations on the field and surrounding ridges, the U.S. Signal Corps operated throughout the Battle. Two of their most important stations were here at the Pry House (headquarters station) and on Elk Ridge (mountain station), the high ground over a mile to the east. The Manual of Signals stated that with a 12-foot staff and 4-foot flag, signals "are easily read at a distance of 8 miles."
Field Hospital
After the battle, the Antietam Valley was described as "one vast hospital." With more than 18,000 soldiers wounded in the two armies, over one hundred field hospitals were established in houses, barns, churches, and tents. Some operated just briefly, others housed the sick and suffering for months. The Pry family home and barn were used to care for the wounded, primarily from the Union Second Corps. Gen. Joseph Hooker was brought to the house briefly after being wounded near the Cornfield before being transferred to Washington, D.C.
[Captions:]
Gen. Israel Richardson was wounded while leading his division at Bloody Lane. His wife and sister cared him in the upstairs bedroom for over a month, until he finally succumbed to his wounds on November 3. During his visit in October, President Lincoln made a point to see Richardson.
Dr. Jonathan Letterman was the medical director for the Union Army of the Potomac and an organizational genius. He restructured the army's medical care in the field and established an ambulance corps that was first successfully instituted at Antietam. His leadership helped bring order to the chaos in the aftermath of the battle.
Erected by National

Photographed by Devry Becker Jones (CC0), April 1, 2025
2. Army Headquarters / Signal Station / Field Hospital Marker
Topics. This historical marker is listed in these topic lists: Communications • Science & Medicine • War, US Civil. A significant day of the year for for this entry is November 3.
Location. 39° 28.551′ N, 77° 42.814′ W. Marker is in Keedysville, Maryland, in Washington County. It can be reached from Shepherdstown Pike (Route 34), on the left when traveling east. Touch for map. Marker is at or near this postal address: 18906 Shepherdstown Pike, Keedysville MD 21756, United States of America. Touch for directions.
Regionally, this marker is in the Baltimore Metro Region and in Western Maryland. It is also in the American Mid-Atlantic, in Appalachia, and specifically in Northern Appalachia. Globally, it is in North America, the Western Hemisphere, the Western World, and the Anglosphere. Historically, it finds itself in what was once one of the original Thirteen Colonies.
Other nearby markers. At least 8 other markers are within walking distance of this marker: Pry Family Upheaval (here, next to this marker); Second Army Corps (approx. Ό mile away); Humphreys' Division, Fifth Army Corps (approx. half a mile away); Morell's Division, Fifth Army Corps (approx. half a mile away); Fifth Army Corps (approx. half a mile away); a different marker also named Second Army Corps (approx. half a mile away); Richardson's Division, Second Army Corps (approx. half a mile away); Prys Mill Bridge (approx. 0.6 miles away). Touch for a list and map of all markers in Keedysville.
Other markers no longer nearby. Pry Family Upheaval (was here, next to this marker but has been replaced with another marker now near it); a different marker also named Army Headquarters / Signal Station / Field Hospital (has been replaced with this marker).
Credits. This page was last revised on April 1, 2025. It was originally submitted on April 1, 2025, by Devry Becker Jones of Washington, District of Columbia. This page has been viewed 187 times since then and 21 times this year. Photos: 1, 2. submitted on April 1, 2025, by Devry Becker Jones of Washington, District of Columbia.