How did Abraham Lincoln perform aerial reconnaissance during the Civil War?

ANswer: BALLOON Corps

Wiki - The Union Army Balloon Corps was a branch of the Union Army during the American Civil War, established by presidential appointee Thaddeus S. C. Lowe. It was organized as a civilian operation, which employed a group of prominent American aeronauts and seven specially built, gas-filled balloons to perform aerial reconnaissance on the Confederate States Army.
 
Slate - On April 19, 1861, just as the drums of war had begun to sound in Washington, Thaddeus Lowe launched his small, businesslike balloon the Enterprise from a vacant lot in the heart of Cincinnati. Lowe’s ambitious plan was to fly 500 miles due east over the Allegheny Mountains, and to land in Washington, ideally perhaps on the front lawn of President Lincoln’s White House. Here he might offer his services to the Union cause, and outflank rival aero­nauts who hoped to do the same. In the event, he met a rebel breeze, and ended up much farther south, having skirted Kentucky and Tennessee, and finally touching down after 650 miles near Unionville in the heart of the seceded state of South Carolina.
On landing, Lowe found the Civil War already declared and decidedly in progress. The local cotton farmers were not impressed by his flying skills or his Yankee accent. On the contrary, he was arrested as a spy for supposedly carrying dispatches from the Union North, blatantly piled in the corner of his balloon basket. With some difficulty, due to local illit­eracy, he was able to demonstrate that these dispatches were actually a special balloon edition of the Cincinnati Daily Commerce, and thereby escape being lynched.
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