USMC024 Marine Kneeling Firing Carbine
From mid 1941 onwards virtually every USMC officer and senior NCO was issued with the M1 Carbine, Officially it was to replace the pistols and submachine guns previously used by them.
For many however it was still useful, practical and plain old common sense to carry at least one additional weapon and that was usually the Colt 1911 A1 automatic pistol.