Aerial reconnaissance goes back to the early era of ballooning, and forward to the latest reconnaissance satellites and unmanned aerial vehicles(UAV). After the French Revolution, the new rulers became interested in using the balloon to observe enemy manoeuvres and appointed scientist Charles Coutelle to conduct studies using the balloon L'Entreprenant, the first military reconnaissance aircraft. The balloon found its first use in the 1794 conflict with Austria, where in the Battle of Fleurus the gathered information and the demoralizing effect on the Austrian troops ensured victory for the French troops.
After the invention of photography, primitive aerial photographs were made of the ground from manned and unmanned balloons, starting in the 1860s, and from tethered kites from the 1880s onwards. An example was Arthur Batut's kite-borne camera photographs of Labruguière starting from 1889.
Ludwig Rahrmann in 1891 patented a means of attaching a camera to a large calibre artillery projectile or rocket, and this inspired Alfred Maul to develop his Maul Camera Rockets starting in 1903. Alfred Nobel in 1896 had already built the first rocket carrying a camera, which took photographs of the Swedish landscape during its flights. Maul improved his camera rockets and the Austrian Army even tested them in the Turkish-Bulgarian War in 1912 and 1913, but by then and from that time on camera-carrying aircraft were found to be superior.
The first use of airplanes in combat missions was by the Italian Air Force during the Italo-Turkish War of 1911-1912. On 23 October 1911, an Italian pilot flew over the Turkish lines in Libya to conduct history's first aerial reconnaissance mission, and on 1 November 1911, the first ever aerial bomb was dropped on the Turkish troops in Libya.
On 16 October 1912 a Bulgarian Albatros aircraft was used to perform Europe's first reconnaissance flight in combat conditions, against the Turkish lines on the Balkan peninsula, during the Balkan Wars of 1912-1913.
During the First World War, photo reconnaissance, now called IMINT, was one of the early uses of the aeroplane. Aviators such as Fred Zinn evolved an entire range of new flying and photography techniques to use the new technology in the equally new environment of trench warfare.
Before the Second World War the conventional wisdom was to use converted bomber types for airborne photo reconnaissance. These bombers retained their defensive armament, which was vital since they were unable to avoid interception. Later it was found that day bombers required a fighter escort.
In 1939 Sidney Cotton and Flying Officer Maurice Longbottom of the RAF were among the first to suggest that airborne reconnaissance may be a task better suited to fast, small aircraft which would use their speed and high service ceiling to avoid detection and interception. Although this seems obvious now, with modern reconnaissance tasks performed by fast, high flying aircraft, at the time it was radical thinking. They proposed the use of Spitfires with their armament and radios removed and replaced with extra fuel and cameras. This led to the development of the Spitfire PR variants. Spitfires proved to be extremely successful in their reconnaissance role and there were many variants built specifically for that purpose. Later De Havilland Mosquitos were also used.
The reconnaissance plane that had the earliest and greatest influence for the Americans in WWII was the F-4, a factory modification of the P-38E which replaced the four guns and cannon with four high-quality K-17 cameras. Some 120 F-4 and F-4As were hurriedly made available by March 1942, reaching the 8th Photographic Squadron in Australia by April (the first P-38s to see action.) The F-4 had an early advantage of long range and high speed combined with the ability to fly at high altitude; a potent combination for reconnaissance. In the last half of 1942, Lockheed would produce 96 F-5As, based on the P-38G. The Lightning in its reconnaissance role was so well-liked by military strategists that hundreds of gun-equipped P-38s were field modified into camera-toting F-5 variants. Later in the war, the Mustang F-6 arrived, eventually becoming the dominant reconnaissance model flown by the US in the ETO.
Immediately after World War II, long range aerial reconnaissance was taken up by adapted jet bombers – such as the English Electric Canberra, and its American development, the Martin B-57 – capable of flying higher or faster than the enemy. After the Korean War, RB-47 aircraft were used. These were at first converted B-47 jet bombers, but later these were purposely built RB-47 reconnaissance planes. They did not carry any bombs. They had large cameras mounted in the belly of the plane, and with a truncated bomb bay used for carrying flash bombs.
The onset of the Cold War led the development of highly specialized and secretive strategic reconnaissance aircraft, or spy planes, such as the Lockheed U-2 and its successor, the SR-71 Blackbird (both from the United States). Flying these aircraft became an exceptionally demanding task, as much because of the aircraft's extreme speed and altitude as it was because of the risk of being captured as spies. As a result, the crews of these aircraft were invariably specially selected and trained.
In the United States, the Department of Homeland Security currently has MQ-1 Predator drones patrolling U.S. borders, and is currently studying how to implement drones monitoring highways, ports, the electrical grid, and other critical infrastruture.