Caudron G4 flying above the Yser polder
From Wikipedia
The Caudron G.4 is a French biplane with twin engines, widely used during World War I as a bomber. It was designed by René and Gaston Caudron as an improvement over their single-engined Caudron G.3. The aircraft employed wing warping for banking. The first G.4 was built in 1915, and it was manufactured in France, England and Italy. It was the world's first twin-engine aircraft to be widely used, starting in March 1915.
The Caudron G.4 was used as a reconnaissance bomber against the German Empire. Later, when Germany developed a fighter force, the aircraft was used for night bombing.
The G.4 was in use in Belgium, France, Finland, Italy, Portugal, the United Kingdom, and the United States.
During the Battle of the Yser in the First World War, by opening the sluices, part of the polder west of the Yser was flooded with seawater between Nieuwpoort and Diksmuide to provide an obstacle to the advancing German Army and keep westernmost Belgium safe from German occupation. The Yser river itself never overflowed its banks
