Wikipedia:
The French 75 mm field gun was a quick-firing field artillery piece adopted in March 1898. Its official French designation was: Matériel de 75mm Mle 1897. It was commonly known as the French 75, simply the 75 and Soixante-Quinze (French for 75, literally "sixty-fifteen"). Initially, the French 75 had been designed as an anti-personnel weapon system for delivering large volumes of time-fused shrapnel shells on enemy troops advancing in the open. After 1915 and the onset of trench warfare, other types of battlefield missions demanding impact-detonated high-explosive shells prevailed. By 1918 the 75s became the main agents of delivery for toxic gas shells. The 75s also became widely used as truck mounted anti-aircraft artillery. They were also the main armament of the Saint-Chamond tank in 1918.
The French 75 is widely regarded as the first modern artillery piece.[1][2] It was the first field gun to include a hydro-pneumatic recoil mechanism, which kept the gun's trail and wheels perfectly still during the firing sequence. Since it did not need to be re-aimed after each shot, the crew could fire as soon as the barrel returned to its resting position. In typical use, the French 75 could deliver fifteen rounds per minute on its target, either shrapnel or melinite high-explosive, up to about 5 miles (8,500 m) away. Its firing rate could even reach close to 30 rounds per minute, albeit only for a very short time and with a highly experienced crew.
At the opening of World War I, in 1914, the French Army had about 4,000 of these field guns in service. By the end of the war about 12,000 had been produced. It was also in service with the American Expeditionary Forces (AEF), which had been supplied with about 2,000 French 75 field guns. Several thousand were still in use in the French Army at the opening of World War II, updated with new wheels and tires to allow towing by trucks rather than by horses. The French 75 set the pattern for almost all early-20th century field pieces, with guns of mostly 75 mm forming the basis of many field artillery units into the early stages of World War II.
It is not to be confused with the Schneider-manufactured modele 1907 and "modele 1912" made for the French cavalry and the export market, and its 1914 modification. Although they used the original French 75's ammunition, these privately manufactured Schneider guns were lighter, smaller, and mechanically different.

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