Brothers Joseph-Michel and Jacques-Étienne Montgolfier, paper manufacturers by trade, demonstrated their invention publicly for the first time, sending a linen-and-paper balloon filled with hot air aloft before a crowd of townspeople and local dignitaries. The flight proved that lighter-than-air travel was possible and set off a European sensation, leading within months to the first manned flights.
The Montgolfier brothers had been experimenting with paper bags and smoke for months, initially believing that burning wool and moist straw produced a special gas they called 'Montgolfier gas' rather than simply hot air. On June 4, 1783, they unveiled a much larger craft in the market square of Annonay: a taffeta-lined balloon roughly 30 feet in diameter, sealed with alum for fireproofing.
Filled from a fire pit beneath its open neck, the balloon swelled and lurched upward, climbing an estimated 6,000 feet and drifting for ten minutes before descending in a nearby field, to the astonishment of local officials who signed a notarized account of the event.
News reached Paris within weeks, prompting royal interest and a rapid escalation: by September the brothers demonstrated a flight before Louis XVI at Versailles carrying a sheep, a duck, and a rooster, and by November, human passengers ascended for the first time. The Annonay flight is generally regarded as the opening act of human aviation.