It was based on a design by American firearms inventor John Browning, and completed by Dieudonné Saive at FN Herstal.

FN Herstal named it the "High Power" in allusion to the 13-round magazine capacity, almost twice that of other designs at the time, such as the Walther P38 or Colt M1911.

[7] FN Herstal continued to build guns for the Allied forces by moving their production line to a John Inglis and Company plant in Canada, where the name was changed to "Hi Power".

Other names include GP (after the French term grande puissance) or BAP (Browning Automatic Pistol).

[10] From 2019 to 2022, with new Belgian Hi-Powers no longer being built, new clones were designed by various firearm companies to fill the void, including GİRSAN, TİSAŞ, and Springfield Armory, Inc.

The 2022 "FN High Power" incorporated a number of entirely new features such as a fully ambidextrous slide lock, simplified takedown method, enlarged ejection port, reversible magazine release, wider slide serrations, different colored finish offerings, and 17-round magazines.

In contrast to popular belief, the new FN High Power might resemble a modern Hi-Power, but it is, in fact, a different design.

The French military required that: This last criterion was seen to demand a caliber of 9 mm (0.35 in) or larger, a bullet mass of around 8 g (120 gr), and a muzzle velocity of 350 m/s (1,100 ft/s).

Browning built two different prototypes for the project in Utah and filed the patent for this pistol in the United States on 28 June 1923, granted on 22 February 1927.

They hoped to find a military contract which would in turn help them finance a production line, essentially through the same process as their previous FN M1900 pistol.

By 1931, the Browning Hi-Power design incorporated the same 13-round magazine, a curved rear grip strap, and a barrel bushing that was integral to the slide assembly.

The Belgian Army showed a definite interest and bought 1,000 pistols based on this prototype for field trials.

Production began in late 1944 and they were on issue by the March 1945 Operation Varsity airborne crossing of the Rhine into Germany.

Inglis High-Powers made for Commonwealth forces have the British designation 'Mk 1' or 'Mk 1*' and the manufacturer's details on the left of the slide.

[19] In 2018, FN announced they would end production of the Mark III Hi-Power, which was expensive to produce and had been assembled in Portugal to cut costs.

On 18 January 2022, after a four-year hiatus, FN announced they would resume production of the Browning Hi-Power, albeit with a number of upgraded features.

The most significant changes included opening up the top of the slide to increase the size of the ejection port to ensure reliable feeding and ejection, incorporating an ambidextrous slide lock and reversible magazine release, a completely different takedown that is faster and simpler, and redesigning the barrel and recoil spring.

Other changes FN made include removing the magazine disconnect safety, adding an extended beavertail and redesigned hammer to eliminate the issue of hammer bite, several sets of redesigned grips, new sights compatible with the FN 509 dovetail pattern, wider slide serrations, different colored PVD or stainless steel finish offerings and 17-round magazines.

SDS CEO Tim Mulverhill stated: "The market demand has not been met for historically accurate Hi-Powers.

The SDS Inglis line is essentially a more military accurate version of the now-discontinued Regent BR9, and it is a fully interchangeable Mark III design.

The adjustable sights are still available on commercial versions of the Hi-Power, although the shoulder stock mounts were discontinued during World War II.

In contrast, a single-action pistol can only be fired with the hammer in the cocked position; this is generally done when a loaded magazine is inserted and the slide cycled by hand.

The downward movement of the barrel disengages it from the slide, which continues rearward, extracting the spent case from the chamber and ejecting it while also re-cocking the hammer.

After the slide reaches the limit of its travel, the recoil spring brings it forward again, stripping a new round from the magazine and pushing it into the chamber.

During World War II, it was manufactured by Inglis of Canada for Allied use, and by FN in occupied Belgium for German use.

These P35s lack the provision of the lanyard ring – the left side pistol grip for a Mark I is fully covered unlike those produced for military and law enforcement use.

The main distinguishing (visual) feature of the Mark III is the absence of the water drain hole below the muzzle on the forward face of the slide.

The reception to this was positive and so six prototype frames were machined from solid aluminum and two were sent to each of the Canadian, American, and British governments for testing.

The Canadian and British governments concluded that sand and dirt caught between the steel slide and aluminum frame substantially increased wear.

[40] The Hi-Power was the pistol issued to all British Armed Forces throughout the Cold War era and up to Iraq and Afghanistan conflicts.