page_title: Fort Corcoran
section_title: Union Army Balloon Corps
hierarchical_section_title: Fort Corcoran / Wartime use / Union Army Balloon Corps
caption_attribution_description: English: Intrepid being cross-inflated from Constitution in a spur-of-the-moment attempt to get the larger balloon in the air to overlook the imminent Battle of Seven Pines. The balloon Intrepid, one of six to eventually be constructed by Thaddeus Lowe and the Union Army Balloon Corps. Français&#160;: l’Intrepid gonflé à partir du Constitution. 日本語: インターピッド号、セブンパインズの戦いを観測するためにコンスティチューションのガスも使って充填しているところ.
context_page_description: Fort Corcoran was a wood-and-earthwork fortification constructed by the Union Army in northern Virginia as part of the defenses of Washington, D.C. during the American Civil War. Built in 1861, shortly after the occupation of Arlington, Virginia by Union forces, it protected the southern end of the Aqueduct Bridge and overlooked the Potomac River and Theodore Roosevelt Island, known as Mason's Island.
  The fort was named after Colonel Michael Corcoran, commander of the U.S. Fighting 69th Infantry, Irish Brigade 69th New York Volunteer Regiment, one of the units that constructed the fort.
  Fort Corcoran was home to the Union Army Balloon Corps and the headquarters of the defenses of Washington south of the Potomac River, and served throughout the war before being dismantled in 1866. Today, no trace of the fort remains, although the Arlington County government has erected a historical marker at its site.
context_section_description: From September 1861 through August 1863, Fort Corcoran served as the official headquarters for the Union Army Balloon Corps, commanded by Thaddeus S. C. Lowe, who had been appointed to the position by President Lincoln. A civilian organization, the Balloon Corps performed limited aerial observation duties for the Army of the Potomac.
  In late July 1861, Lowe inflated a balloon in Washington with hopes of providing aerial coverage for the impending Battle of Bull Run, but a violent storm buffeted the inflated balloon and delayed Lowe until word of the Union defeat reached him on the road. Lowe subsequently decided to make a detour to Fort Corcoran, reaching it on July 27. Over the next few days, he repeatedly ascended in the balloon in order to make maps of the surrounding area and gather intelligence about Confederate troops advancing on Washington.
  The information gathered was valuable enough that Lowe was ordered to construct larger balloons by an officer of the U.S. Army's Topographic Engineering Corps. The first of these was complete by mid-August, and was subsequently ordered to report to Fort Corcoran. Beginning August 30, 1861, Lowe's new balloon made daily ascents to monitor the movements of Confederate troops that had moved north following the Battle of Bull Run. By September 11, 1861, General F.J. Porter, in command of the forces in the area of Fort Corcoran was impressed enough by Lowe's daily reports to write, "You are of value now."
  On September 24, 1861, Lowe went beyond simple observations when he actively directed the fall of artillery fire from nearby Camp Advance on Confederate positions near Falls Church, three miles away. The agreed-upon signaling system was simple, but effective: "If we fire to the right of Falls Church, let a white flag be raised in the balloon; if to the left, let it be lowered; if over, let it be shown stationary; if under, let it be waved occasionally." This event was the first time in American history that an aerial observer actively directed artillery fire.
  Because of these and other successes, Lowe was authorized to build four additional balloons and the needed inflation equipment. However, Lowe's initial successes proved difficult to recreate in field conditions, and aside from limited successes, such as at the Battle of Seven Pines, the utility of the Balloon Corps was limited. In addition, jurisdictional squabbles arose between Lowe's civilian command and the military officers under whom he worked. By early 1863, Lowe had grown tired of dealing with military minutia and left the Corps, returning to civilian research. The Balloon Corps fell to the command of less-capable individuals and was eventually eliminated in August 1863.
caption: The balloon Intrepid, one of six to eventually be constructed by Thaddeus Lowe and the Union Army Balloon Corps.
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