Williamsport in Washington County, Maryland — The American Northeast (Mid-Atlantic)

C & O Canal Aqueduct

Stonewall Changes Course

— Antietam Campaign 1862 —

C & O Canal Aqueduct Marker image. Click for full size.

Photographed by Craig Swain, June 3, 2007

1. C & O Canal Aqueduct Marker

Inscription. On September 10, 1862, Gen. Robert E. Lee ordered Gen. Thomas J. “Stonewall” Jackson and a detachment of 15,000 men, about two-thirds of the Army of Northern Virginia, to capture the Union garrison at Harpers Ferry and secure Confederate lines of communication with Virginia. At first, Jackson planned to follow the Sharpsburg Road from Frederick to the Potomac River, but then he decided to cross the river here at Williamsport, where he could easily engage the nearby Federal garrison at Martinsburg, Virginia. When Jackson’s column forded the river here on September 11, the outnumbered garrison fled to Harpers Ferry. By taking the longer route, however, Jackson found himself behind schedule. He did not capture Harpers Ferry until September 15 and rejoined Lee on the Antietam battlefield barely in time to save the Confederate army.

Erected by Maryland Civil War Trails.

Topics and series. This historical marker is listed in this topic list: War, US Civil. In addition, it is included in the Chesapeake and Ohio (C&O) Canal, and the Maryland Civil War Trails series lists. A significant historical month for this entry is September 1863.

Location. 39° 36.047′ N, 77° 49.658′ W. Marker is in Williamsport, Maryland, in Washington County. It can be reached from West Potomac

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Street. Located in the Conococheague Aqueduct section of the Chesapeake and Ohio Canal National Park. Touch for map. Marker is at or near this postal address: 205 W Potomac St, Williamsport MD 21795, 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 the North Atlantic Region,

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 5 other markers are within walking distance of this marker: Williamsport (here, next to this marker); Gettysburg Campaign (here, next to this marker); Cushwa Basin/Williamsport (here, next to this marker); Life on the Canal (a few steps from this marker); C&O Canal (about 500 feet away, measured in a direct line). Touch for a list and map of all markers in Williamsport.

Other markers no longer nearby. Creating a National Park (was a few steps from this marker but has been confirmed missing); a different marker also named Williamsport (was within shouting distance of this marker but has been confirmed missing); The Conococheague Aqueduct Restoration (was within shouting distance of this marker but has been confirmed missing); Connecting People and Places (was within shouting distance of this marker but has been confirmed missing); Conococheague Creek Aqueduct (was within shouting distance of this marker but has been confirmed missing).

More about this marker. On the lower left is a photograph of the aqueduct. A map of Jackson's route is on the right. A portrait of General Jackson is on the lower right.

Photographed by F. Robby, June 29, 2016

2. C & O Canal Aqueduct Marker

View north along the canal towpath, towards the Conococheague Aqueduct. This marker is the one closest of the three shown in this photo.

The Conococheaque Aqueduct image. Click for full size.

Photographed by Craig Swain, June 3, 2007

3. The Conococheaque Aqueduct

This "water bridge" was completed in 1834. Jackson attempted, without success, to destroy the aqueduct with artillery, and the structure stood intact until the 1920s when damaged in a canal boat accident.

Conococheague Aqueduct image. Click for full size.

Photographed by F. Robby, June 29, 2016

4. Conococheague Aqueduct

The Potomac River side (west) of the aqueduct as it crosses the Conococheague River.

Credits. This page was last revised on September 25, 2025. It was originally submitted on June 10, 2007, by Craig Swain of Leesburg, Virginia. This page has been viewed 2,515 times since then and 15 times this year. Photos: 1. submitted on June 10, 2007, by Craig Swain of Leesburg, Virginia. 2. submitted on July 15, 2016, by F. Robby of Baltimore, Maryland. 3. submitted on June 10, 2007, by Craig Swain of Leesburg, Virginia. 4. submitted on July 15, 2016, by F. Robby of Baltimore, Maryland. • J. J. Prats was the editor who published this page.