In simple terms, strategic bombing involves employing bombers to strike directly at key industrial, economic or political targets within an enemy's country which may affect its capacity to wage war, rather than attacking their armed forces. The concept was first developed by the Germans during the First World War in response to their inability to invade or effectively blockade Britain on the sea. The resulting raids on London, employing large aircraft and airships, caused alarm amongst Britain's government and population that was far out of proportion to the damage caused. Britain's response was to prepare an even greater aerial offensive and the Royal Air Force (RAF) was created as an independent service in April 1918 to carry it out. The war ended before the potential of strategic bombing could be tested.

Throughout the twenty years prior to the start of the Second World War, many of the RAF's senior officers remained committed to the concept of strategic bombing and several believed it could win a war outright. When the Second World War began Britain was unwilling to unleash its bombers for fear of provoking German attacks on British cities, but as defeat in continental Europe loomed in May 1940, it turned to bombing as the only means to strike back at Germany. Strategic bombing by Britain, and later the United States, then continued without respite for the rest of the war.

The vulnerability of the heavy bombers to enemy fighters meant that the British bombed by night. With the equipment then available, however, the smallest feasible targets were entire towns, and even these often proved difficult to locate. This resulted in the adoption of a policy known as "area bombing" in which whole towns were targeted. These attacks were designed not only to destroy the German war economy but also to undermine civilian morale and, thus, the Nazi government.

When the United States entered the war in Europe it bombed by daylight in the belief that it allowed them to mount precision attacks. Their bombers, however, proved just as vulnerable to fighters as those of the RAF. The American solution was to develop long-range fighters to provide protection all the way to the target and back. The advent of these fighters meant an almost continuous bombing offensive against Germany - the United States Army Air Force (USAAF) by day and the RAF by night. The accuracy of Bomber Command's attacks progressively increased with the introduction of electronic navigation and targeting aids from 1942 onwards. By late 1944 its aircraft could devastate relatively small targets with a degree of accuracy that far exceeded the daytime efforts of the Americans, but area bombing continued to be pursued as a valid strategy until the end of the war. Bombing of targets in occupied Europe and Italy was also conducted as the part of the offensive. The USAAF were strong advocates of these attacks, whereas Bomber Command saw them as a diversion from their main effort.

All told, the strategic bombing offensive cost the Allies approximately 100,000 aircrew and inflicted up to one million fatal casualties upon Germany. Raids over occupied Europe killed more civilians than had the Germans in Britain. Debate still continues over the merits and the morality of the strategy underpinning the offensive. It was only at the very end of the war that the offensive came close to achieving its ultimate objective of destroying the German war economy, and German morale never seemed in danger of collapsing. The offensive's greatest achievement was that it drew the German air force into battle, pulling it away from supporting the fighting fronts on the ground, and destroyed it. The offensive thereby contributed to Allied air supremacy that proved critical to victory on the ground, and facilitated even greater destruction by the bomber forces.