The Colt Commander was developed in the 1950’s as a smaller version of the M1911A1 service pistol. As the name suggests, the idea was to have a gun that was smaller for upper ranking officers who were unlikely to actually see combat.
The Colt Commander was the first 1911-style pistol to be chambered in 9mm. The models made for the US Army were all chambered in .45 ACP.

Additional Resources:
Comments, suggestions, contributions? Let me know