A combat shotgun is a shotgun issued by militaries for warfare. The earliest shotguns specifically designed for combat were the trench guns or trench shotguns issued in World War I. While limited in range, the multiple projectiles typically used in a shotgun shell provide increased hit probability unmatched by other small arms. History While the sporting shotgun traces its ancestry back to the fowling piece, which was a refinement of the smoothbore musket, the combat shotgun bears more kinship to the shorter blunderbuss. Invented in the 16th century by the Dutch, the blunderbuss was used through the 18th century in warfare by the British, Austrian, Spanish (like the Escopeteros Voluntarios de Cadiz, formed in 1804 or the Compañía de Escopeteros de las Salinas, among others) and Prussian regiments, as well as in the American colonies. As use of the blunderbuss declined, the United States military began loading smaller lead shot (buckshot) in combination with their larger bullets, a combination known as "buck and ball". The buck and ball load was used extensively by Americans at the Battle of New Orleans in 1814 and was partially responsible for the disparate casualty rates between American and British forces. The advantage of this loading was that it had a greater chance of hitting the enemy, thus taking wounded soldiers out of a fight. The disadvantage of this load was that the buckshot did not cause as severe wounds at longer ranges, and contemporary accounts show many of the British wounded recovering quickly as they had been struck by the buckshot rather than the ball. Fowling pieces were commonly used by militias, for example during the Texas Revolution. However, buck and ball worked as well or better in standard or even rifled muskets. Buck and ball loads were used by both sides of the American Civil War, often by cavalry units. The development of the repeating pump-action shotguns in the 1890s led to their use by the US Marines in the Philippines insurrections and by General "Black Jack" Pershing's pursuit of Pancho Villa, and "riot" shotguns quickly gained favor with civilian police units, but the modern concept of the combat shotgun was fully developed by the American Expeditionary Forces during World War I. The trench gun, as it was called, was a short-barreled pump action shotgun loaded with 6 rounds containing antimony hardened 00 buckshot, and equipped with a bayonet. The M1897 and M1912