The development of the Ca.1 to the Ca.2 suggested the benefits of increasing amounts of power to the very sound airframe. The Ca.3 was a development of Ca.2, by replacing the two engines mounted on the booms with the same Isotta-Fraschini engine that had been used as the central, pusher engine on that design.
The prototype flew in late 1916 and was soon put into production. Known to Caproni at the time as the Caproni 450 hp, the Italian Army designated it the Ca.3. In Caproni's post-war redesignation, it became the Ca.33. Somewhere between 250 and 300 of these aircraft were built, supplying the Italian Army and Navy (the latter using the type as a torpedo bomber), and the French Army. Late in the war, Robert Esnault-Pelterie built the type under licence in France, building an additional 83 (some sources say only 19) aircraft.
Note: there is some variation in published sources over early Caproni designations. The confusion stems, in part, from three separate schemes used to designate these aircraft - Caproni's in-house designations of the time, those used by the Italian Army, and designations created after the war by Caproni to refer to past designs.
Armament was 2 to 4 Revelli 6.5mm or 7.7mm machine guns, 1 in front ring mounting and 1, 2 or sometimes even 3 in an upper ring mounting. Bombs suspended under the hull.
Apart from the Italian Army, Caproni Ca.3s were also used in British squadrons, before the introduction of the Handley Page Type O bombers. Original and licence-built ones were used by France (original Caproni were used in French CAP escadres, licence-built examples in CEP escadres). They were also used by the American Expeditionary Force.
Some of the Ca.36Ms supplied after the war were still in service long enough to see action in Mussolini's first assaults on North Africa.
This plane entered the memoires by a tragical event. In 4th May 1919 french general dr. Milan Rastislav Stefanik, minister of war in Czechoslovak republic, flew in Caproni 450hp from Campo Formido near Udine to Bratislava (capital of Slovakia). He had an accident, probably because of failure of the air-blast cooling of Isotta engine. One of the engines exploded and the plaine headcrashed the ground. Gen. Stefanik and three members of Italian attendance were dead on scene. They are still being speculations whether was the plaine shot by the anti-aircraft company, or it was the engine failure. This could had been done either because they had mistaken italien flag on the wings with Hungarian, or in direct order from higher posts, but this is just conspiracy, they say, that Stefanik planned changes in new Czechoslovakian Government. Most likely it was carelessnes of the officer Piccione, who underestimated the disposition of the landing runway. It was wet, and after first attempt to land, the pilot took off when he spotted the wet ground and wanted to land further on, but in these maneuver many planes noticed cooling failure, as it was the most likely reason of the fatal crash of Caproni 450hp with gen. dr. Milan Rastislav Stefanik.