Reconnaissance/reconnoitre (from Old Fr.: reconnoître, to recognize). The art of reconnaissance may be said to pre-date all military combat. It is hard to imagine that the first two combatants in war, whoever they might have been, embarked upon conflict without attempting to gain some knowledge of the capabilities of their enemy. The Chinese military philosopher Sun-tzu noted as much in c.500 bc, claiming that ‘what enables a good general to strike and conquer … is foreknowledge’. This fundamental point is ignored by a senior officer at his peril. The method of obtaining information through reconnaissance has changed over time thanks to technological advances, but the underlying principles remain the same.
The collection of intelligence can be performed by the oldest form of military technology, the human eyeball, or the most advanced, including satellite systems. It is carried out in all theatres of war, on land, at sea, and in the air. It may be conducted within a short distance of the enemy or with the opposing sides many miles apart. Reconnaissance may not lead to combat, since it may simply keep commanders appraised of enemy capabilities; it may be the precursor to attack; or it may follow an attack to assess the effectiveness of operations.
Obtaining reconnaissance information is obviously of the highest importance. As a result, it is desirable that the units employed to collect information return to convey what has been learned, and it is unusual for reconnaissance units to seek contact with the enemy. Reconnaissance is normally conducted by small groups, individual aircraft, or naval vessels detached from their main force. Trying to define a specific paradigm for reconnaissance is impossible, since the gathering of information of all types is useful. A section of infantry, operating within a short distance of their lines, may be used to carefully advance to seek out but not to engage the enemy. Cavalry, by virtue of its mobility, proved to be a valuable source of information, a principle continued by this arm today, albeit in light armoured vehicles. Again, it would be unusual for cavalry on reconnaissance to seek to engage the enemy, since the value of reconnaissance units lies not in the damage they can inflict upon the enemy, but the provision of information which permits commanders to plan how to damage the opposition to best effect. However, there are times when information must be fought for, and sometimes an enemy's strength may be tested by reconnaissance by battle.
As technology developed and the range over which battles were fought increased, it became increasingly difficult to obtain the necessary intelligence. This was particularly true during WW I. Static warfare prevented observation of anything beyond the front line by ground forces, which could not hope to outflank the enemy to observe unseen. As a result of this, reconnaissance had to be provided by the nascent technology of the aircraft. Although initially compelled to rely upon the human eye, the development of suitable photographic equipment enabled air services, particularly those of Britain, France, and Germany, to obtain information at a great distance behind the enemy lines. The importance of aerial reconnaissance was enhanced as longer-ranged aircraft were developed, allowing flights over enemy territory. This remained the case throughout WW II, in spite of increased opposition from anti-aircraft artillery. The fundamental problem faced by reconnaissance aircraft in the modern era has been the increasing sophistication of air defences, which has led to the refinement of equipment to allow the aircraft to acquire imagery from long range at oblique angles. In addition, reconnaissance has moved into the non-visual spectrum, with electronic reconnaissance. The monitoring of enemy signals traffic and radar networks by specialized aircraft has increased. The development of the satellite has moved photographic and electronic reconnaissance into a new sphere. Satellites can provide images or information at regular intervals thanks to their orbit, or can remain fixed above a certain target to monitor developments. Their invulnerability to interception makes them a worthwhile addition to the reconnaissance armoury of any nation which can afford them.
Although of considerable use, aerial and satellite reconnaissance cannot provide all necessary information. The gathering of information on the ground is still essential: technology has not made redundant the more traditional forms of acquiring intelligence. Simply knowing an enemy's deployment or technical capability may not be enough: human intelligence (HUMINT) helps provide a judgement of his morale and fighting effciency. Intelligence gleaned from monitoring enemy communications— SIGINT—also has a valuable part to play. A commander may be able to fight successfully even when lacking in certain areas such as numbers or equipment, but a commander deficient in information is heading for disaster. This is as true now as it ever was.
— David Jordan
