Fort Corcoran - Planning and Construction

Planning and Construction

Over 13,000 men marched into Northern Virginia on the 24th, bringing with them "a long train of wagons filled with wheelbarrows, shovels, &c." These implements were put to work even as thousands of men marched further into Virginia. Engineer officers under the command of then-Colonel John G. Barnard accompanied the army and began building fortifications and entrenchments along the banks of the Potomac River in order to defend the bridges that crossed it. By sunrise on the morning of the 24th, ground had already been broken on the first two forts comprising the Civil War defenses of Washington — Fort Runyon and Fort Corcoran. Fort Corcoran was named after Colonel Michael Corcoran, commander of the 69th New York Volunteer Regiment, one of the units that constructed the fort. The 69th New York, part of the famed Irish Brigade, went about its work with high spirits, exemplified by the actions of Father Thomas Mooney, the 69th's chaplain. After the fort's cannon were emplaced, Mooney baptized them and was promptly recalled by New York's bishop, who took a dim view of the sacrilegious action.

Despite the limited nature of the two forts, Barnard reported that the work was difficult. "The first operations of field engineering were, necessarily, the securing of our debouches to the other shore and establishing of a strong point to strengthen our hold of Alexandria. The works required for these limited objects (though being really little towards constructing a defensive line) were nevertheless, considering the small number of troops available, arduous undertakings."

In the seven weeks that followed the occupation of Arlington and the beginning of work on Fort Corcoran, Barnard and his engineers were forced to focus virtually all of their effort on Corcoran and Runyon, owing to the limited resources available. By the time Barnard was beginning to focus his efforts on tying Corcoran and Runyon into an entire belt of fortifications, his engineers were drawn off by the approach of the Confederate Army and the incipient First Battle of Bull Run.