This is a Brazilian Colt Government Model. It belonged to BG Jack Babcock. He became an advisor to the Brazilian Minister of War in 1944 and took the opportunity to purchase this pistol. 

 I bought General William Ghormley's Distinguished Service Medal at his estate sale when I was thirteen years old. The medals were split up. Ten years later, I was given his pistol belt. Twenty-five years after the sale, the remaining medals were sold again and I bought them. By coincidence, I met a collector who had his pistol, and we made a deal. It took thirty years, but I reunited the group. 

BG Daniel Johnson enlisted in the Army and served in the Occupation of Japan. He later became an officer and retired as a Brigadier General in the Army Reserve. He was issued this Rock Island Arsenal M15 General Officer Pistol.