There is perhaps no other weapon in the conscious of the public that can command the respect of a 12-gauge shotgun. A riot-length model (most commonly fitted with a 20" barrel but more broadly interpreted to include any length between 21" and the legal minimum at 18 ½") is about as readily apparent in function as a double-bit ax or a shovel; a man carrying the former is looking to cut timber, a man carrying the latter is looking to dig, and presumably a man carrying a riot gun is looking to join a fight or put an end to one.
Today, advances in firearms technology have put the shotgun into a tenuous position. A good percentage of men who regularly go armed for the purpose of close-in work prefer the higher rates of fire, larger capacities, and lower recoil of intermediate-caliber carbines, fifty yards (with practice) is not an unreasonable distance for handgun work, and outside the pastime of breaking clays or hunting game birds the shotgun seems to have slipped into the unenviable position of being the jack of all trades and the master of none.
But it was not always thus. In the era before wide presence of semi-automatics, detachable magazines, and all manner of whiz-bang gadgetry available to the contemporary shooter the shotgun was the the tool of choice for a man expecting trouble. The spread of shot meant he was more likely to put lead on target. In doubles, the presence of a second barrel meant another shell ready in case of misfire (or determined miscreants). Likewise, early autoloaders and pumpguns without a trigger disconnect allowed a single shooter to put a good deal of lead in the air in a hurry. Moreover, a shotgun is an imposing specimen - and this goes especially for the view from the business end.
The double gun being a perfectly adequate choice of the era (and still today, in practiced hands) the dedicated fighting shotgun couldn't truly come about without two crucial developments. The first was that of cased ammunition. The second, the growing prevalence of repeating arms which began appearing in the boom following the American Civil War.
Introduced in 1882, the Spencer repeating shotgun was the first commercially viable pump action to appear on the market. Somewhat ungainly, it was slow to catch on and not produced in great numbers. Five years later Winchester introduced their Model 1887, a lever-action design from a Utahn by the name John Moses Browning. Even at the height the levergun's popularity the 1887 was not the smashing commercial success the powers at Winchester might have hoped. It did, however, demonstrate the advantages of a single-barrel design feeding from an underslung tubular magazine.
This carried over some six years later when Winchester - again producing a Browning design - first began offering the Model 1893, a pump chambered for 2½" shells. Sales were generally good, but in comparatively short order the 1893 was dropped from the catalogue in favor of the improved Model 1897, now in the familiar 2¾" chambering and featuring numerous tweaks and refinements in respect to its predecessor.
The timing was fortuitous. With the end of the Spanish-American War in 1898 the United States found itself taking the first halting steps into the limelight as a world power. Upon the cessation of hostilities America made its first territorial gains in the Philippines, Guam, and Puerto Rico, and soon thereafter began coming to grips with the hard truths of being a colonial power; Filipinos, expecting recognition of their independence per a pre-war agreement, rose violently when denied after the fact.
The dustup that came to be known as the Philippine Insurrection revealed any number of shortcomings in the U.S. military. Famously, the .38 Colt revolvers issued to occupation troops proven unequal to the task of putting down a doped-to-the-gills Moro warrior emerging from the jungle waving a machete, who often succumbed to his wounds after killing the hapless shooter. This led first to the re-issue of the heavier Single Action Army in .45 Colt; Stateside, it prompted development on what were to become the 1911 service pistol and the 1903 rifle (and, respectively, the .45ACP and .30-06 rounds). Meantime, it was decided that if two rounds of double-ought buckshot were good for stopping a fight, then five must be even better. The U.S. government began acquiring the new Winchester shotguns, and the 1897's legacy as a martial arm was off to a credible start.
This reputation was alive and well in 1917 when the first men of the American Expeditionary Force set foot in France. Then in its third year, the Great War was long since established as a static conflict. Once the grand Napoleonic formations of men met and promptly shot each other to bloody rags in 1914, battle lines settled and and grew stagnant. It was a misery unlike any seen before - no longer a rifleman's fight, conducted at range and firing in ordered volleys, but a fixed killing ground ruled by artillery, gas, and chattering machine guns. Exchanges of lead at close quarters were sudden and fierce, often a result of nighttime trench raids with small teams infiltrating neighboring enemy positions in search of prisoners and intelligence.
With rifles too ungainly in the confines of a trench and most machine guns too heavy to move rapidly as support, trench fighting devolved into a brutish short-range affair. Pistols, grenades, knives, and clubs that harkened more to the medieval era than the contemporary times were weapons of choice. It was in this type of combat that a short-barreled shotgun would prove invaluable, and as the AEF arrived in-theater so too did a uniquely American solution: a standard Winchester riot gun, outfitted with perforated barrel shroud and lug to accept the same bayonet as the U.S. 1917 rifle. Thus refitted for modern war, shotguns in this configuration entered the doughboy parlance as 'trench guns'.
In this guise the Winchester served with distinction, being used to good effect by Army and Marine Corps units through the end of the war and well beyond (to include limited service as late as Viet Nam). So effective was the weapon that it was deemed cruel and offensive and thereafter formally protested by the Germans...those delightful people who introduced the world to poison gas, unrestricted u-boat warfare, and zeppelin raids on English population centers.
In this guise the Winchester served with distinction, being used to good effect by Army and Marine Corps units through the end of the war and well beyond (to include limited service as late as Viet Nam). So effective was the weapon that it was deemed cruel and offensive and thereafter formally protested by the Germans...those delightful people who introduced the world to poison gas, unrestricted u-boat warfare, and zeppelin raids on English population centers.
Hell...a recommendation like that's got to count for something.