Observation balloons

An observation balloon is a type of balloon that is employed as an aerial platform for intelligence gathering and artillery spotting. Use of observation balloons began during the French Revolutionary Wars, reaching their zenith during World War I, and they continue in limited use today.

Historically, observation balloons were filled with hydrogen. The balloons were fabric envelopes filled with hydrogen gas, whose flammable nature led to the destruction of hundreds of balloons on both sides. Observers manning these observation balloons frequently had to use a parachute to evacuate their balloon when it came under attack. To avoid the potentially flammable consequences of hydrogen, observation balloons after World War I were often filled with non-flammable helium.

Typically, balloons were tethered to a steel cable attached to a winch that reeled the gasbag to its desired height (usually 1,000-1,500 metres) and retrieved it at the end of an observation session.

The first military use of observation balloons was by the French Aerostatic Corps during the French Revolutionary Wars, the very first time during the Battle of Fleurus (1794). The oldest preserved observation balloon, L'Intrépide, is on display in a Vienna museum. They were also used by both sides during the American Civil War (1861–65) and continued in use during the Franco-Prussian War (1870–71). Balloons were first deployed by the British Army's Royal Engineers during the expeditions to Bechuanaland in 1884 and Suakin in 1885. They were also deployed during the Second Boer War (1899–1902), where they were used in artillery observation at the Battle of Magersfontein and during the Siege of Ladysmith.

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