The .45 ACP cartridge was a development of necessity. It was designed in 1904 by one of our most prolific firearms geniuses, the brilliant John Moses Browning, to be used in his newly designed Colt semi-automatic pistol.
At the time of the Moro Rebellion in the Philippines, the US Cavalry there was armed with double action handguns chambered for both the .45 Colt and .38 Long Colt cartridges, and the .30-40 Krag rifle. The Moro insurgents proved to be a formidable opponent. Both the .38 Long Colt and the .30-40 Krag cartridges proved to be largely deficient in stopping the Moro warriors effectively.
Largely as a result of the Philippine experience and the results of the Thompson-LaGarde testing of 1904, the US Army and the US Cavalry decided that a minimum of .45 caliber would be required for any new military handgun.
At the time, Colt and John Browning were working on a .41 caliber cartridge for Browning's newly designed pistol. They then modified both the pistol and cartridge resulting in the Model 1905 pistol and the new .45 ACP cartridge.
After considerable experimentation involving several different government departments and other involved American companies, they settled on a load consisting of a 230-grain bullet with a muzzle velocity of 850 fps.
In 1906, the army decided to conduct a series of tests to determine the best pistol to be adopted as the military's new sidearm, and invited the firearms industry to submit their example to be tested. Models from three manufacturers made it through the first series of tests, Colt, DWM, and Savage. One company, DWM, even though they had made the cut in the first round, withdrew, leaving a shoot-off (no pun intended) between Colt and Savage for the gold medal.
The second trial was held in 1910, with the Browning designed Colt handily coming out on top. It was then adopted as the Model 1911, now an icon among handguns. From that time until 1985, the 1911, and the modification of it, the 1911 A1, chambered for the .45 ACP, was the standard firearm of the US military, a very long time, attesting to the success of the handgun for military applications. It was eventually replaced by the Beretta M9 9mm, although some units retained the 1911A1 as their primary sidearm.
As a youngster, surplus 1911A1s were common items in gun shops, pawnshops and at gun shows. They were not very expensive and surplus .45ACP ammo was plentiful and cheap. The first one I can remember that came my way in a trade was a surplus 1911A1 that someone had chrome plated and fitted with simulated stag grips.
I got the pistol and 100 rounds of surplus military ammo for something like $25.00. That would have been in the late 1950s I believe. At the time, I thought the combination was the cat's meow. In retrospect, it was pretty hideous although it shot well and would have served its purpose admirably if needed.
The ballistics of the .45 ACP is pretty anemic by today's standards. Even though the standard military load of a 230-grain FMJ bullet at 830 fps is, by most assessments, formidable, ammo manufacturers are continually tinkering with the round.
The SAAMI max pressure is set at 21,000 psi. Higher and higher velocities seems to be the holy grail of loading ammo these days, and consequently, SAAMI approved a pressure increase to 23,000 psi for .45 ACP +P ammo. Why, I can't say.
For home defense and self defense purposes, it has done very nicely without the increased pressure. It seems to me that the increased pressure and therefore velocity, is a solution to a nonexistent problem.
Added to that opinion, there is a downside to adding pressure to the cartridge. While the standard military .45 ACP cartridge, fired in a Colt 1911A1 or one of the many, many equivalent clones, is by no means a horrifically recoiling combination, it does require training to master. Add to the recoil, and one must also add to the training.
The most common complaint that I heard during my military career when on the pistol range with the 1911A1 firing standard ball ammo, was that it kicked too hard.