Aerial warfare came of age during the First World War. Initially aircraft were employed for reconnaissance duties and their success in this role soon led to other aeroplanes being armed for offensive use to protect armies from such intelligence gathering flights. In turn reconnaissance machines armed themselves for defence and air battles (nicknamed 'dogfights') became a common sight over the battlefronts. Specialist fighter and bomber aircraft developed alongside the reconnaissance machines in a rapidly developing aerial arms race. Advances in aerial photography and air to ground communications enhanced the information gathering capacity of reconnaissance flights and made their interception increasingly important. Communications developments included the first use of air-to-ground signalling by wireless allowing aircraft to direct artillery fire. Tactical air support for ground operations was also practised with the bombing and strafing of enemy troops and transport. The later stages of the war also witnessed small-scale airdrops of supplies to ground units.

Aircraft became increasingly important and were used to some extent in every operational theatre. They also caught the public imagination, especially the exploits of fighter pilots, and the cult of the 'ace' was born with high 'scoring' pilots such as Albert Ball and Manfred von Richthofen ('The Red Baron') becoming household names. During the Second World War pilots such as Douglas Bader, 'Johnnie' Johnson and Adolf Galland also fulfilled people's need for heroes. The coming of war in 1939 saw greater advances in the employment of military air power. Advances in aircraft design and weaponry greatly improved the aircraft's capacity to engage in ground support, anti-shipping and anti-submarine operations. The development of transport aircraft allowed airborne forces to be transported for actions behind enemy lines. In the post-war period the helicopter has brought to this latter role a significantly greater flexibility.

Air warfare is effectively an arms race accelerated by the demands of wartime, each side striving for ascendancy via technical innovation. Speed, manoeuvrability, range, payload and tolerance of extreme conditions have all influenced aircraft design. Of vital importance was the revolution in aero engine technology beginning in the mid-1930s that resulted in the world's first jet fighters entering service with the RAF and Luftwaffe in 1944. German research also led to the development of jet and rocket-powered missiles in the form of the V1 and V2. By the 1960s missile technology was linked to nuclear weapons. Refined forms of air-to-air and air-to-ground missiles also became the principal aircraft armament though quick firing cannon are still carried by many military aircraft.

Technological breakthroughs in the development of radar and electronic navigation were also of immense significance. The integration of an extensive network of radar stations with an efficient communications systems linked to squadrons of modern fighters was of great importance in securing the defeat of the Luftwaffe during the Battle of Britain in 1940. Airborne radar, quickly developed in the wake of night bombing, vastly increased the likelihood of successful interceptions by night fighters. By 1943, radar-equipped German night fighters posed such a threat to the British night bombing offensive that much effort was directed towards the development of countermeasures designed to obscure radar echoes or jam the German system completely. These were the forerunners of the sophisticated electronic counter-measures developed to defend today's aircraft from guided missile attack. The Second World War bomber offensive against Germany also witnessed the introduction of navigational aids such as 'Gee', H2S and 'Oboe', enabling night bombers to locate their targets with increasing accuracy. Today, computer technology has led to sophisticated guidance systems and 'smart' bombs designed, in theory, to attain very high levels of precision targeting.

The complex military and moral issues of 'precision' bombing came to the fore with the development in the 20th century of the military doctrine of strategic bombing. Unlike other forms of military air power, strategic bombing does not directly target an enemy's armed forces. Instead it seeks to attack targets far removed from the battlefield, including factories, transport networks and centres of government and population. The aim is to destroy an enemy's willingness to wage war by cutting off his armed forces from vital supplies and breaking the morale of his people. The aerial bombing campaigns of the First World War gave a hint of things to come and during the inter-war years airpower theorists sought to evolve how most effectively to exploit the bomber. Theories were put to the test during the Second World War, which saw strategic bombing reach its destructive pinnacle. German bombing of Warsaw (1939), Rotterdam (1940) and the sustained 'Blitz' on Britain (1940-41) was later eclipsed by RAF Bomber Command and American massed raids on Germany. Similar highly destructive raids were launched by American aircraft on Japanese cities. But neither precision strikes on individual targets or bombing large built-up areas achieved the goals claimed by its supporters. Only with the dropping of the atomic bombs on the Japanese cities of Hiroshima and Nagasaki in August 1945 did strategic bombing come close to delivering a decisive blow to the enemy. These monumental events opened the nuclear age that soon saw the USA and Soviet Union confronting each other, with huge arsenals of nuclear weapons. The development of long-range missiles, first exemplified by the German V1 and V2, allowed the awful destructive power of nuclear weapons to be delivered into the heart of an enemy country with little chance of interception. Fear of retaliatory strikes, at the heart of the doctrine of 'Deterrence' helped ensure that such ultimate expressions of strategic bombardment were never launched.

The Museum's 'War in the Air' collections relate predominantly to the roles played by British and Commonwealth forces during the First and Second World Wars and are drawn from both official and private sources. This allows the subject to be studied from the command level down to the experiences of individual service men and women.