This guide provides sources on the development of military sidearms (revolvers, and later semi-automatic pistols) which began to be adopted by armies in the 1800s. Multi-shot sidearms first appeared beginning around the mid-1500 with matchlock and wheellock weapons. They were adapted to the ignition systems used then and on up to the modern revolver. These systems included the matchlock, wheellock, flintlock, percussion, and metallic cartridges. Early pistols took various forms and had one or more barrels. These included double barreled pistols and "duckfoot" pistols with three or four barrels, "pepperbox" pistols and derringers, and transitional revolvers with multiple barrels or chambers. These pistols required rotating the barrel or cylinder by hand to place the next powder and bullet load into firing position.

The percussion revolver was first developed in the 1830s by Samuel Colt. These pistols featured a revolving cylinder, and a single-action cocking mechanism that rotated the cylinder when the hammer was re-cocked for each shot. The Colt Paterson (1836) available in .28 to .36 caliber, was followed by a number of other Colt black powder percussion revolvers including the .44 Walker Colt, the .44 Dragoon Model, the .36 and .38 1851 Navy Model, and various compact .31 pocket models. Colt's percussion revolvers saw widespread use in the American Civil War (1861-1865) and in the following decades. Pistols produced by Remington Arms were also widely used in the war and after. Among these were the Remington Model 1858 in .31, .36, and .44 caliber. The New Army Model of the 1858 was chambered in .44, the slightly smaller framed Navy 1858 was chambered in .36, and a pocket version fired a .31 caliber bullet.

The use of percussion revolvers began to diminish as modern rim-fire and center-fire cartridge revolvers were developed. They were developed as single-action revolvers that required pulling back the hammer to cock it before firing, and as double action revolvers which could be fired either by pulling the trigger or by cocking the hammer and then pulling the trigger. The best known single-action was the .45 1873 Colt Single Action Army. Its barrel length varied from 7 1/2 inch models issued to the US Army, to the famous Peacemaker version with its 5 1/2 inch barrel, to a three-inch barreled Sheriff's Model. A few 12 inch barreled examples were produced, known as Buntline Specials. They were commissioned by lawman Ned Buntline as presentation pieces. Other examples of revolvers, some which came into use earlier than the 1873 Colt were the 1856 .42 LeMat with a nine-round cylinder and .63 shotgun barrel, the 1857 .22 rimfire Smith & Wesson Model 1, and the 1870 .44 Smith & Wesson Model 3 "Schofield." Colt and other gunmakers continued to improve upon designs with double-action revolvers. Colt produced such double-action revolvers as the Colt Model 1878 in various calibers, and the .38 Model 1892. The 1892 was the first double-action revolver issued to the United States military. Improvements to the 1892 requested by the Army allowed Colt to produce improved versions in 1892, 1894, 1896, 1901 and 1903.

European nations supplied their armies with domestically produced revolvers and some imported American revolvers. The German 10.6x25mmR M1879 and M1885 Reichsrevolver was used by the German Empire until 1908 when the semi-automatic 9mm P-08 Luger was adopted. The Reichsrevolver remained in widespread use through World War I (1914-1918) and saw limited use in World War II (1939-1945). Great Britain's armed forces employed the .442 Beaumont-Adams revolver, 1856-1880. It was replaced by the 11.6mm Enfield Mk I and Mk II revolvers which remained in service until 1911. Webley & Scott supplied British forces with such handguns as the 1887 .455 Webley Mk I revolver and the 1915 455 Mk VI. Webley revolvers remained in British service from 1887 to 1970. France's military used the revolver model 1873 and model 1874 Chamelot-Delvigne, and the Model 1892 revolver, known also as the Lebel revolver or St. Etienne 8mm. The Belgian 7.62x38mmR Nagant M1895 was used by the Russian Army in large numbers as well as by the Belgian military. Italy armed its troops with the 10.35mm Model 1874 Army Service Revolver and the Bodeo 10.35mm Model 1889 revolver. The Bodeo was in use from 1891 through the end of WWII. It was also manufactured in Spain and the German Wehrmacht of WWII used it as an alternative weapon. In 1877 Japan's military began using a Russian-made revolver developed in Smith & Wesson's .44 caliber; the Second Model Russian Revolver. Another pistol, the domestically developed 9mm Type 26 Revolver, contained features of the French Model 1892. It was manufactured from 1893 to 1925.

Technological advances in firearms design began to move away from revolvers to self-loading, semi-automatic pistols. In this new system, a pistol was loaded by pushing a stripper clip of rounds in the pistol's empty magazine or by loading a removable, reusable box magazine or "clip" into the pistol's empty magazine, located inside the pistol's handgrip. A round was chambered by pulling back on a semi-automatic pistol's charging slide or toggle which grabbed a round from the magazine and on its returning forward motion, inserted the round into the firing chamber. When the trigger was pulled, firing the pistol, the recoil pushed the slide or toggle back to automatically self-load the next round. Each pull of the trigger fired one round as long as ammunition was available in the magazine. Early examples came onto the market in the very late 1800s and very early 1900s, and with the onset of World War I, the demand for these new, faster-firing pistols literally exploded.

Initial development of semi-automatic sidearms came from European inventors in Italy, Austria-Hungary and Germany, and Colt in the United States. These efforts resulted in pistols such as the Italian Glisenti 9mm Model 1910, the Austro-Hungarian 9mm Steyr M1912/P16, the German 9mm Mauser C96 (1896), also called the Broomhandle Mauser or the Bolo, and the 9mm Luger P-08 (1908). An artillery version of the Luger P-08 was also produced using a longer and heavier barrel. It could be used as a carbine when attached to its wooden holster that doubled as a shoulder stock, and the artillery Luger could mount a 32-round snail drum.

The United States military's first universally adopted semi-automatic service pistol was the Colt Model 1911.45 ACP (Automatic Colt Pistol). The M1911 was developed from the .38 ACP Colt Model 1900, designed by John M. Browning (1855-1926). The M1900 saw service in the Philippines during the Moro Rebellion or US-Moro War (1899-1913). The M1911 remained the service pistol of all US military branches for over 70 years, through four major wars. Production of the M1911 for the military alone totaled around three million examples, with millions more for the civilian market. The M1911 was replaced by the Beretta M9 9mm pistol in the mid-1980s. Some branches' special operations units retained the Colt M1911 far longer. The last of these operators retired the M1911 in 2023.

World War II created another spike in the firearms industry by creating the need for a vast increase in the manufacturing of handguns. Along with the continued production of proven models by manufacturers Luger, and Mauser, German manufacturer Walther Arms produced several pistols adopted by German military and police forces. The 32 PP (1929), 32 PPK (1931), the 9mm Walther Model P38 (1938), as well as other models from the 1910s and 1920s saw service in WWII and beyond. The P38's total wartime production was 1,144,000 examples. The Belgian-made FN (Fabrique Nationale) Browning Hi-Power semi-automatic pistol, introduced in 1935, saw service in WWII by both the Allies and Germany, and continued in wide-spread use after the war. Its users had an advantage in its larger capacity magazine (13 rounds, plus one chambered round). It remains the Canadian Army's official service pistol. Japan had not had great success with developing a semi-automatic until a design by Colonel Kirijo Nambu was introduced. The First Model 8mm Nambu (1906), also known as the Type A, was a combination of borrowed design points from the Italian Glisenti Model 1910, the Mauser c96 and Nambu's own ideas. It was followed by a 8mm Second Model Nambu or Type B, with a larger trigger guard for a gloved finger, and the smaller 8mm Baby Nambu. The Soviet Union relied heavily on the 7.62mm 1930 Tula-Tokarev Pistol or TT-30. It was the most-produced Soviet World War II-era pistol along with the reliable 1895 Nagant Revolver.

The technological advances made during World War II and the advent of the Cold War (1947-1991) continued, resulting in further refinements throughout the world. These advances incorporated the use of non-metal materials such as plastics, polymers, fiberboard, and other synthetic materials to make weapons lighter, stronger and more easily repaired, resistant to metal corrosion caused by gunpowder, and undetectable by metal detection technology. Higher capacity magazines (14 rounds on up) became standard, especially for those pistols chambered in 9mm. These advances produced such pistols as those made by Austrian manufacturer Glock, American maker Ruger Arms, and Swiss/German manufacturer SIG Sauer. Modern revolvers continue to be produced by Colt, Smith & Wesson, and by Ruger Arms.

This guide does not include materials on the topics of gun control, assault weapon bans, or mass casualty shootings.