On June 16, 1861, meteorologist Thaddeus Lowe floated 500 feet above the Columbian Armory in Washington and sent the first telegraph message from an aerial station to President Lincoln over a wire running into the White House. Backed by Joseph Henry of the Smithsonian, Lowe went around the usual procurement channels, and Lincoln personally took him to General Winfield Scott. His appointment angered rival aeronauts. John Wise held a commission from the topographical engineers but tangled his balloon in brush on the way to Bull Run, and John LaMountain, a former partner, attacked Lowe in the press and argued for free flight, while Lowe insisted on tethered balloons that could telegraph reports in real time.

After the coal-gas balloon Union was hauled for nine hours over the Chain Bridge and then lost to a gale, Lowe built portable generators with the Washington Navy Yard: copper-lined wagon tanks where sulfuric acid and iron filings produced hydrogen, cooled through water before entering a varnished silk envelope. On September 24, 1861, he directed unseen artillery fire on Confederate camps at Falls Church, and he launched balloons from the converted coal barge George Washington Parke Custis. At Seven Pines in 1862 he spotted Samuel Heintzelman’s corps being cut off and filled the balloon Intrepid from the smaller Constitution through a camp kettle with its bottom cut out.

• An early Confederate hot smoke balloon was lifted by burning oil-soaked pine cones and spun into uncontrolled flight when its tether was cut.
• The story of a Confederate balloon sewn from donated silk dresses is a myth, as the silk was bought from merchants.
• Edward Porter Alexander signaled from a Confederate balloon using wigwag flags.
• Under Captain Cyrus B. Comstock, Lowe’s pay was cut from $10 a day in gold to $3, and he resigned in 1863, with the Army dropping balloons by that August.
• In 1864 Brazil offered Lowe the rank of major general to run a balloon corps in its war with Paraguay, and he declined.