Some planners, such as Billy Mitchell, expressed disappointment that the war had ended before aviation had demonstrated its potential. Nevertheless, they examined what evidence there was. They then attempted to predict the future of technology and to imagine future conflicts. Although most of the prophets worked for their governments, they often went outside of the military to broadcast their theories. They were published in the aviation journals of the time. France’s Revue de l’aeronautique militaire was the first, but Italy’s Rivista Aeronautica, which debuted in 1925, quickly became the main forum for Giulio Douhet, his supporters, and critics.

The nearly 20 years of peace following World War I, which saw only minor colonial uprisings and the Spanish Civil War, did not provide too many chances for the prophets to test their theories. Yet the war had given them enough evidence to decide that to end a future conflict quickly and with minimal loss of life, a bombing campaign was necessary, directed not at the troops, but at the cities of the enemy. The idea of bombing to deprive the enemy of the means and will to continue to fight became known as "strategic bombing."

Bombing cities made sense to the prophets. Well-trained troops had already proved that they had the endurance to withstand protracted attack. Yet, civilians in cities had demonstrated the opposite. Trenchard claimed that civilians "are not disciplined and it can not be expected that they will stick stolidly to their lathes and benches." During the Gotha raids on London, the city had gone through a minor panic; many had fled to the countryside for safety, and the newspapers had run columns criticizing the government’s inability to protect the capital. In studying the effects of the Gotha raids, the prophets theorized that increased, intensified attacks, which included incendiary and gas bombs, would cause a populace to rise up against its government. This would result in chaos, with loss of productivity, riots, looting, and eventually a toppling of the government leading to surrender. The country that would emerge victorious from a bombing war would be the country whose populace could endure the bombings while delivering greater damage to the other side.

 
Hugh Trenchard, one of "the Prophets."

A bombing campaign would be as much a psychological as a physical battle. Trenchard studied the effects of British bombing attacks on towns in Germany and estimated that the psychological damage was twenty times greater than the material. And interestingly, living under the threat of an attack was as damaging to civilian morale as an actual attack. The German city of Trier experienced only seven raids, but underwent more than 100 air raid alarms--each one demanding that people leave their jobs or beds and hurry to shelters in fear. Workers who spent the night in shelters listening for the sound of bombs did not come to work the next day or were too tired to perform their jobs properly. In this way, bombing could destroy a nation’s production without destroying its factories. 

Basing a military theory on targeting civilians posed wrenching moral and ethical questions. Douhet noted, "Humanity and civilization may avert their eyes" in thinking about bombing civilians.  But the prophets knew that in the modern democratic world, a nation went to war on behalf of its citizens, not a king or emperor." Spaight defined the new target as "the sovereign people who war and it is their nerve and morale which must be broken." The greatest concentration of people was in the cities, and so they were the best targets.

With the build-up of air forces, the prophets knew that a single massive bombing would not win a war. Instead, the plan, as outlined by Douhet, was first to gain air superiority by destroying an enemy’s air force, preferably while on the ground. The next step was to bomb, concentrating on the industrial sections of cities, in order to prevent the enemy from rebuilding its military. Since bombsights were extremely inaccurate at the time, a massive amount of bombs would have to be dropped over a large rectangular area on the theory that one might hit the actual target. Civilians would have to take shelter in order to avoid stray bombs. Once the nation had surrendered, ground troops would move in to occupy the country.

 
Although "the Prophets" didn't express their philosophy until after World War I, Caproni advocated strategic bombing during the war and built aircraft to support that view. This photo shows the Caproni Ca33 over Northern Italy.

Douhet is the prophet known as the "father of air power." An Italian artilleryman, he evidently never learned to fly although he was chief of his country’s air section in 1913 and 1914. His strong ideas about the uses of bombing made many claim that the industrialist and aircraft manufacturer Gianni Caproni was funding him to ensure a future market for Caproni bombers. He published frequently in the Rivista Aeronautica and in 1931, released his book Command of the Air, with a second, more strident, edition published in 1937. It was not translated into English until 1942, although unofficial translations were circulated around the English and American Air Corps. Despite this, top American and British officers claimed never to have seen his writings and maintained that he did not influence their bombing campaigns during World War II.

 
Caproni provided a well-developed rationale for bombing such enemy targets as industrial plants, port facilities, railway bridges, junctions, and marshalling yards as a way to eliminate an enemy's capability to sustain a war effort. The Caproni Series 4 triplane bomber, shown in this photo, was much larger than the earlier Ca 3 although its performance was not markedly better.

Both the U.S. and English air forces used the theory of strategic bombing in their struggles to gain independence from the other military service branches. The Royal Air Force had gained independence during World War I but was threatened with losing it during the interwar period. Advocates of an independent U.S. air force felt that, because strategic bombing does not depend on partnerships with ground or naval troops, the needs of an air unit were often neglected when the people overseeing the budget were more interested in tanks or battleships. It was felt there had to be a separate service branch, with its own budget, hierarchy, and staff. To keep a nation safe, an independent air force capable of winning the war by bombing was necessary for national security. But not until after World War II and the advent of the nuclear bomb did the United States have an independent air force.

Even in their own writings, the prophets sometimes expressed remorse at the barbarity of their ideas, as later in life Spaight told militaries to "make machines and not mankind the mark of your attack." Strategic bombing may have seemed cruel, but for the prophets, a quick war with bombing cities was better than an extended war with the carnage and horrors of World War I. Since then, there have been a number of wars and military conflicts, but strategic bombing is considered a viable theory that is still argued and debated today.