Image of Thaddeus Lowe via Wikipedia
On September 7, 1861, Union Major General George McClellan, commander of the Army of the Potomac, went ballooning with Thaddeus Lowe.
Lowe had been posted near Arlington, Virginia, at Fort Corcoran since his balloon was completed on August 28. He conducted aerial reconnaissance and took several generals, reporters and artists aloft. Just two days before McClellan's first flight, Lowe had gone aloft with Generals Irvin McDowell and Fitz John Porter.
McClellan observed the Confederate fortifications at nearby Munson's Hill and Clark's Hill, and got a view of Washington similar to this one that appeared in the July 27, 1861 edition of Harper's Weekly. It is unclear how many flights McClellan made, but he saw the value of the balloon as a military asset, and Lowe soon received an order to construct four more balloons and purchase portable gas generators.