I'm referring to the self-loading pistol.

In April of 1897, John Moses Browning was granted his first patent for a self-loading pistol. As was his practice, he offered it to Colt, which, while not keen on diverging from revolvers, felt it should hedge its bets.

In 1899, Browning sold the Belgian firm of Fabrique Nationale (FN) on a design for a blowback pistol in which the weight of the slide and tension of the recoil spring held the breech closed until the bullet had left the barrel. The slide then reciprocated, extracting and ejecting the spent case. The slide was then pulled forward by the recoil spring, and as it moved forward, it stripped a new cartridge out of the magazine and chambered it. Introduced as the Pistolet Automatique Browning Mle. 1900, the gun's popularity was such that because of it the Browning name became synonymous with the word "pistol" in many parts of the world.

The Model 1900's cartridge--the 7.65mm Browning--became even more famous than the pistol itself. It utilized a semi-rimmed case 17mm long loaded with a 71-grain full-metal-jacketed (FMJ) bullet. Rated velocity was 900 fps. While underpowered, it was well suited to blowback-operated pistols and was embraced by European military and police forces.

In 1902, recognizing the popularity of the Belgian-made pistol, Colt began marketing another Browning blowback design as the .32 Caliber Model 1903 Pocket Pistol. Realizing the dislike Americans traditionally displayed towards the metric system, Colt renamed the 7.65mm cartridge the .32 Automatic Colt Pistol (.32 ACP). Colt's M1903 proved an instant hit.

The next entrant into the U.S. pocket-pistol market was the Savage Model 1907 pistol, which used a retarded blowback system to lock the breech. It also proved quite popular, and that in turn encouraged yet another American manufacturer to take the plunge. That firm was Harrington & Richardson.

In 1874, Gilbert Harrington and William Richardson established their gun-making company in Worcester, Massachusetts, to produce small, solid-frame revolvers with single-action, sheath triggers that were chambered for the .32 rimfire cartridge. These revolvers were of better quality than most of the competition, earning H&R a good reputation. By the 1890s, the most popular type of personal/home-defense/police-duty handgun was the hinged-frame/top-break, automatic-ejecting revolver, and to address this lucrative market, H&R introduced such a revolver in 1897. While loath to diverge from the proven market for revolvers, H&R saw the increasing popularity of the Colt and Savage self-loading pistols and, in the finest tradition of the Yankee entrepreneur, set about producing a competing product.

In 1905, the famous British revolver-making firm of P. Webley & Scott introduced a series of blowback-operated pistols in .25 and .32 calibers that were designed by William Whiting. The .32 model was adopted by a number of police departments in Great Britain and throughout the empire.