FWIW, in WWI, many troops were issued pistols/revolvers, much of the reason M1911 pistols were scarce and Colt and S&W were asked to produce revolvers for the .45 ACP cartridge. At that time, squad leaders, assistant squad leaders, all company grade officers, machinegunners, assistant machinegunners, MPs, etc., etc. all carried pistols. Many of them couldn't hit anything with a handgun. The carbine was intended to replace almost all those pistols with a short, light rifle that would be easier to hit with and yet easy to carry for men whose duties involved other than direct engagement with the enemy or whose primary weapon was something other than the infantry rifle.