The Aqueduct Bridge dates to the antebellum period, when Alexandria comprised part of the federal District of Columbia. Alexandria, a port city, desired to benefit from the trade that was moving along the C&O Canal to rival Georgetown. In 1830, a group of Virginia merchants formed the Alexandria Canal Company. They sought to extend the C&O Canal to the Virginia side of the Potomac River, and from there, to Alexandria. The Aqueduct Bridge, known as the Alexandria Aqueduct or Potomac Aqueduct, was designed to carry the canal across the river. Construction on the bridge and the Alexandria Canal began in the early 1830s and was completed in 1843. The bridge, an engineering marvel of the 19th century, cost a staggering sum of around one million dollars. With the extension of the C&O Canal to Cumberland, Maryland in 1850, the Aqueduct Bridge played a key role in bringing coal from western Maryland to the the port at Alexandria.
The Aqueduct Bridge featured prominently at the start of the Civil War. Virginia voters officially approved secession on May 23, 1861, and in the early morning hours of May 24, Union soldiers moved to occupy Alexandria and Arlington Heights. A Federal column including the 5th, 28th, and 69th New York crossed the Aqueduct Bridge into Virginia. Not long afterward, the Union Army constructed Forts Corcoran, Bennet, and Haggerty to guard the approaches to Aqueduct Bridge from the Virginia side of the river. These forts comprised part of what would become the ring of defenses built to protect Washington during the war.
|The Aqueduct Bridge from the Washington side, with the C&O Canal in the foreground, ca. 1862-65 (courtesy of Library of Congress).|
The tow-path of the aqueduct did indeed furnish a narrow passageway to horsemen and footmen; but this was far from adequate to the military exigencies. Accordingly, early in the winter of 1861-'62, the water was shut off from the aqueduct and its trough converted into a double-track wagonroad, the floor being overlaid with 4-inch planks and long inclines, on trestles, forming connections with the roads on either side.Eventually three blockhouses and a rifle trench were placed at the Virginia end of the Aqueduct Bridge. The head of the bridge was also enclosed with a stockade to protect more effectively against cavalry raids. The Union Army contemplated placing a shore battery in Georgetown to command the length of the bridge, but decided against this defensive measure. A guard of one officer and thirty men usually covered each end of the Aqueduct Bridge.
|One of the blockhouses near Aqueduct Bridge on the Virginia side (courtesy of Library of Congress).|
Barnard, who oversaw the construction of the the defensive works around the nation's capital, concluded in his report that "the aqueduct served perfectly, throughout the entire period of the war, its new destination, and was recognized as an important and essential adjunct to the 'Defenses of Washington' and to the great military operations in Virginia."
|Another view of the Aqueduct Bridge during the Civil War (courtesy of Library of Congress). This photograph was taken from across the Potomac in Virginia. The Washington abutment is visible where the bridge hits the shore in Georgetown.|
|A side view of the Washington abutment. The arch to the left was expanded in 1889 to accommodate the Washington branch of the Baltimore & Ohio Railroad.|