The Army had previously been using the .38 Long Colt, and the cartridge's relatively poor ballistics were highlighted during the Philippine–American War of 1899–1902, when reports from U.S. Army officers were received regarding the .38 bullet's inability to stop charges of frenzied Moro juramentados in the Moro Rebellion, even at extremely close ranges.
He was shot four times at close range in a hand-to-hand encounter by a .38 Colt's revolver loaded with U.S. Army regulation ammunition.
The task was assigned to Colonel John T. Thompson of the Infantry, and Major Louis Anatole LaGarde of the Medical Corps.
The tests were conducted at the Nelson Morris Company Union Stock Yards in Chicago, Illinois, using both live cattle outside a local slaughterhouse, as well as some human cadavers.
The first day of testing involved eight live cattle; seven were shot through the lungs using different caliber rounds, and the effects recorded.
... We are not acquainted with any bullet fired from a hand weapon that will stop a determined enemy when the projectile traverses soft parts alone.