Monocacy Aqueduct

The Monocacy Aqueduct of the Chesapeake and Ohio Canal survived a number of Confederate attempts to destroy it.

The Monocacy Aqueduct, which carries the Chesapeake and Ohio Canal over the Monocacy River, was designed by engineer Benjamin Wright. Completed in 1833, the 516-foot long aqueduct, supported by seven arches, was the longest aqueduct on the canal and was considered one of the canal company’s most significant engineering achievements.

From the beginning of the Civil War the Confederates recognized that the C&O Canal could be used as a Union supply line and repeatedly tried to disable it. As early as June 10, 1861 Confederate General Robert E. Lee urged the destruction of the aqueduct as a means to halt canal navigation. During the Maryland Campaign of 1862 the Confederates undertook their most serious attempts to destroy it. After crossing the Potomac on September 4, Brig. Gen. Daniel H. Hill detailed men to destroy the aqueduct, but he lacked black powder and tools sufficient to accomplish the task. On September 9, while encamped near Frederick, Lee sent Brig. Gen. John G. Walker back to the Monocacy with instructions to destroy the aqueduct. Walker had tools and powder at hand, but he found the aqueduct so well constructed that it was “virtually a solid mass of granite.” The drills available were too dull to bore holes for powder charges. He too gave up the attempt. On July 4, 1864, a small band of Confederates from Partisan Ranger John S. Mosby’s command engaged in a skirmish for control of the aqueduct from Union troops who held it. The Rangers drove the Union troops away and burned canal boats, but made no attempt to damage the aqueduct, which survived the war intact.