The Caproni series 4 triplane bomber was much larger than the Ca. 3 series, but its long range performance was not markedly superior to the smaller biplane bombers. The U.S. Navy contracted for the purchase of a number of the triplanes to equip the northern bombing group in Belgium, but the war ended before this was realized. (U.S. Air Force photo)
1917 also saw the Italian bomber come into its own as an important and effective weapon. As production of new aircraft increased, additional squadrons were equipped, trained and deployed against the Austro-Hungarians. The first night raids were conducted in early January and soon became a regular practice. Daylight and night missions of 30 and more Capronis became common, and targets, more and more frequently, were chosen for their strategic importance. Shipyards and docks at Trieste and Pola were badly damaged in a series of attacks, for example, and attacks were made on targets as distant as Fiume and Vienna.
Gianni Caproni, not content to design and build his successful series of bomber aircraft, made serious efforts to develop and advocate a viable doctrine for their employment in combat. In a series of letters and memoranda to leaders of the Allies, he provided a well developed rationale for bombing such enemy targets as industrial plants, port facilities, railway bridges, junctions and marshaling yards, as a means of eliminating an enemy's capability to sustain a war effort. Naturally he offered the Caproni 3-engine bomber as the ideal aircraft for the task. In point of fact, it was the only bomber the Allies had during 1916 and 1917 that was being produced in sufficient numbers and possessing the necessary performance to sustain an intensive bombing campaign. There is considerable evidence that Caproni's effort had substantial influence on the U.S. decision to undertake production of Caproni bombers as a major element of the U.S. war effort. And in fact, a Liberty engine powered version was put into production in the United States, but only five had been produced before the war ended and production was halted.