The Caudron G.4 is a French biplane with twin engines, widely used during World War I as a bomber.

While the Caudron G.3 was a reliable reconnaissance aircraft, it could not carry a useful bombload, and owing to its design, was difficult to fit with useful defensive armament.

In order to solve these problems, the Caudron G.4 was designed as a twin-engined development of the G.3, first flying in March 1915.

[1] While the G.4 had a similar pod and boom layout to the G.3, it had two Le Rhône rotary or Anzani 10 radial engines mounted on struts between the wings instead of a single similar engine at the front of the crew nacelle, while wingspan was increased and the tailplane had four rudders instead of two.

In May 1915, the French aviator Etienne Poulet broke the altitude record with 3 passengers, reaching a height of 5.850 m (19.226 ft).

In Italy, on 9 November 1916, the Italian aviator Guido Guidi set a world absolute altitude record, reaching a height of 26.083 ft (7.950m).

The Caudron G.4 was used to carry out bombing raids deep behind the front line, being used to attack targets as far away as the Rhineland.

Many aces of the First World War also distinguished themselves in air combat aboard Caudron G.4: the French René Pierre Marie Dorme, Jean Chaput, Marcel Vialet, André Martenot de Cordoux, René Pélissier, Joseph Vuillemin, René Doumer, André Jean Delorme, Didier Lecour Grandmaison but also the Russian ace Viktor Fyodorov (three victories aboard a G.4).

The United States government purchased in 1917 a first Caudron G.4 for technical evaluation through the American Ambassador, William Graves Sharp.