On June 18, 1861, T.S.C. Lowe made a tethered observation flight with his gas-filled balloon Enterprise from a spot on the National Mall in front of where the National Air and Space Museum now stands. During this flight, he sent the first telegram ever dispatched from the air to President Lincoln in the White House, describing what could be seen from an altitude of 500 feet. The ascent marked the beginning of an observation balloon corps for the U.S. Army, the first American military aeronautical unit, and the birth aerial reconnaissance in the United States.