Armies in the late 19th century began to use hot-air and gas-filled balloons to enable them to observe enemy positions. The Royal Flying Corps used a large number of balloons on the Western Front. Cheaper to run than aircraft, balloons were winched to various heights by a ground crew. They were organised in groups so that cross-referenced observational readings was possible.
The development of fighter aircraft made life dangerous for balloon crews. As a result, crew members, unlike aircraft pilots, were permitted to use parachutes. However, they were not easy to destroy as normal bullets passed straight the fabric. Also aircraft had to be careful not to get too close as they were in danger of getting entangled in the wires or being shot down by anti-aircraft guns.
Increasing use of incendiary and explosive bullets by aircraft gunners reduced the survival chances of balloon crews. To counteract this, crews were equipped with a powered winch that helped them to bring the balloons down quickly while under attack.
The means for providing the artillery with aerial observation has proved to be insufficient. It has again been shown, as indeed had already been recognized under less difficult conditions, that it would be a great advantage to add a captive balloon and at least two observation aeroplanes to the war establishment of each Field Artillery Brigade (of two regiments).
The numerical superiority of the enemy's airmen and the fact that their machines were better, were made disagreeably apparent to us, particularly in their direction of the enemy's artillery fire and in bomb-dropping.
The number of our battle-planes was also too small. The enemy's airmen were often able to fire successfully on our troops with machine guns by descending to a height of a few hundred metres.