(This takes six minutes to read.)

I know, you must think that I am exaggerating: surely this could not be the source for such a questionable tactic that a contemporary military would reuse continually. Well, I invite you to read this research and judge for yourselves.

Quoting James S. Corum’s ‘The Spanish Civil War: Lessons Learned and Not Learned by the Great Powers’, page 317:

Captain Didier Poulain, a French Air Force reserve officer and regular commentator on air war, […] pointed out that the Spanish war had proven false the Douhetian prophecy that civilian populations could not stand up to air bombardment: “The civil population stands up well to bombardment, and stubbornly refuses to evacuate towns bombed from the air.”¹¹

Pg. 319:

Major George Kenney […] defended Giulio Douhet to critics who claimed that the Spanish war had disproved his bombing theories, arguing that Douhet’s concepts had yet to be truly put to the test in Spain by large-scale attacks against urban populations. Note that Kenney did not defend Douhet in the manner of a true believer in strategic air war, pointing out only that the contrary had yet to be proven.¹⁷

However, in this case Kenney was wrong. In March 1938 the [Fascists] had launched a massive series of air raids against the city of Barcelona, causing considerable damage and more than two thousand civilian casualties. The raid on Barcelona had dwarfed any military bombing previously seen in Europe and was extensively reported on by the world press.

Contrary to the predictions of Douhet, however, civilian morale in Barcelona did not collapse. In fact, the [Fascists’] strategic bombing campaign strengthened the morale of the Spanish Republicans, which had been wavering prior to this point in the war. The bombing of civilian targets enraged the Republicans and helped to harden resistance at the front.

Pg. 321:

Several of the Army officers offered the conclusion—clearly unwelcome to the Air Corps—that the strategic bombing of enemy cities and industries had had no decisive effect in Spain and that civilian populations had quickly learned to adapt to bombardment from the air, a judgment that contradicted the theory of the popular air power prophet Douhet.²⁴

Pgs. 327–9:

[Fascist] Italy entered the Spanish war with its air force doctrine in a state of flux. Although the doctrine was officially based upon the ideas of General Giulio Douhet, Italy’s first Fascist air minister, the concepts had long been disputed by many of the air force officers.

Douhet’s theory of air power argued that the air force had primacy over the other services and that air forces could quickly defeat an enemy nation by bombing its population centers in order to break the morale of the populace. A war fought in this manner, postulated Douhet, could be won quickly and decisively and without the employment of significant ground or naval forces.⁴⁷

However, since the mid-1920s, there had been a lively debate within the [Regia Aeronautica] about the validity of Douhet’s theories. Douhet’s chief opponent was Colonel (later General) Amadeo Mecozzi, who argued that the natural vocation of aviation was joint operations and that it was best employed in interdiction and close support operations rather than strategic bombing.

Mecozzi considered Douhet’s doctrine of targeting civilians instead of soldiers to be immoral and referred to Douhet’s theory as “war against the unarmed.” In the Revista Aeronautica, the journal of the [Regia Aeronautica], Mecozzi initiated an ongoing debate with Douhet in 1926 that continued until Douhet’s death in 1930.⁴⁸

Although the military officially revered Douhet, partly as a matter of Fascist loyalty and correctness, by the early 1930s most of the Regia Aeronautica’s officer corps was inclined to Mecozzi. In 1929 the [Regia Aeronautica] conducted air maneuvers based on Mecozzi’s concepts.⁴⁹

In 1931 the [Regia Aeronautica] established its first ground attack group under Mecozzi’s command.⁵⁰ By the start of the Spanish war, several important steps had been taken to create an air doctrine stressing attack aviation and joint operations.

Spain served as a practical testing ground for the theories of attack aviation. The Breda 65, a heavy single-engine attack aircraft with a 1,000-kg bomb load, had been developed in the mid-1930s in accordance with Mecozzi’s ideas.⁵¹ The Breda 65 was deployed to Spain and proved successful as a dive bomber, which reinforced the officer corps’s preference for attack aviation.⁵²

The Italians in Spain generally conducted interdiction and close support operations in support of the ground and naval forces. The high point in [the Regia Aeronautica’s] effectiveness came in 1938 when Italian air units, attacking in mass in support of Nationalist and Italian motorized units, enabled the Nationalists to make a rapid and successful advance which breached the Republican lines, drove through to the Mediterranean, and isolated Catalonia from the rest of the Spanish Republic. It was one of the signal victories of the war and indicated what an effective air/motorized troop partnership could accomplish.⁵³

The [Fascists] conducted one major strategic bombing campaign in Spain, partly as a test of Douhet’s theories. In March 1938, as it appeared the Republican resistance in Catalonia might collapse completely, Benito Mussolini ordered a massive bombing effort to be made against Barcelona, the capital of Catalonia. It was thought that heavy bombing might destroy faltering civilian morale. Three days of air bombardment damaged much of the city and inflicted over two thousand casualties, in the heaviest bombing of a major city that had been seen in warfare up to that time.⁵⁴

The bombing effort backfired. Foreign observers noted that, rather than breaking the morale of the Catalonians, the ruthless bombing angered the populace and hardened morale.⁵⁵

After the initiation of the strategic bombing campaign, the Republican retreat halted and the Catalonians fought on with renewed enthusiasm. Catalonia would not fall to the Nationalists for another year. Douhet’s theory had been tried and had failed miserably. After Barcelona, Douhet’s concept of strategic bombing was seen as discredited in continental Europe—but not in the U.S. or U.K.

Pg. 333:

One example of how the ground forces felt about the Air Corps obsession with strategic bombing was a two-page article in the Infantry Journal, the most influential U.S. Army journal of the era. The article, “War à la Douhet,” published in the September–October 1937 issue, included a photo montage of dead civilians and bombed cities showing the results of the ruthless air attacks made by the [Imperialists] in China.

The text commented on Douhet’s record as a Fascist leader as well as his theory that the primary target of air power should be the cities of the enemy and not his armed forces. The Infantry Journal pointed out that Douhet was admired by many in the United States—an oblique reference to the Air Corps—and closed with the statement: “Seven years after Douhet’s death, part of his doctrine comes to China.”⁶⁷

Given Douhet’s status in the Air Corps as the “prophet of airpower” and the reverence with which Douhet was—and still is—held by American airmen, the Infantry Journal was not just publishing a critical editorial, but rather was firing a broadside at the Air Corps’s doctrinal foundations. It is little wonder that Air Corps officers were reluctant to listen to the contrary evidence from army officers depicting serious shortfalls in Air Corps equipment and doctrine.

Quoting Jonathan Haslam’s ‘Giulio Douhet and the Politics of Airpower’:

Generals Spaatz, Eaker, Cabell, George, LeMay, and Hansell ‘spiritedly’ denied ‘any direct influence’ from Douhet, according to the noted historian of the U.S. strategic bombing survey, David MacIsaac.⁹⁸ One is left uneasy, however, at what precisely is meant by ‘direct’ influence. They will not have read the original work. But how much of Douhet was absorbed indirectly through Mitchell?

Quondam Chief of the U.S. Air Corps General Henry (‘Hap’) Arnold recalled that in respect of U.S. strategic bombing: ‘The doctrines were still Douhet’s ideas modified by our own thinking in regard to pure defense.’⁹⁹ And Hansell freely admits in his memoirs that while at the Air Corps Tactical School he ‘had been infected’ with his superiors’ — Harold (Hal) George and Kenneth Walker’s — ‘enthusiastic belief in the doctrines of Mitchell, Douhet and Trenchard’.¹⁰⁰

Thus at least two out of MacIsaac’s six appear to undermine the thrust of his assertions. Moreover, Hansell quotes at length and with approval Don Wilson, Director of the Department of Air Tactics and Strategy at the School (1936–40), when he quotes Douhet more than once in the course of outlining a strategy imbued with Douhet’s ideas.¹⁰¹

From Claudio G. Segrè’s ‘Giulio Douhet: Strategist, Theorist, Prophet?’:

During the Gulf War, a big banner in the snack bar at the U.S. Air Command Staff College, Maxwell Air Force Base, Alabama, proclaimed simply: ‘Mitchell and Douhet were right!’

(Emphasis added in all cases.)

Further reading: The U.S. military deliberately copied from the Wehrmacht