John Moses Browning’s .45 caliber pistol, was adopted by the U.S. military in 1911 replacing various revolvers. The M-1911 remained in service until 1987 when it was replaced by the 9mm Italian Beretta designated as the M-9. Many did not see this as an improvement.
Pistols are a support weapon and most Soldiers are not trained to use handguns. One of the results of the ongoing wars is a giant improvement in military handgun training. This World War II era training film shows the how the Army trained soldiers to use the M1911 in combat.
https://youtu.be/Ro7N7dAmjLY
It took guys like Jack Weaver and Jeff Cooper to bring us the modern pistol technique. It took Bill Rodgers to teach the FBI to shoot with two hands. A lot of other great instructors have moved the ball down the field since then.
A big thanks to the guys at VDMA: youtube.com/ptmccain