The 1st Mission Support Command has its origins in the placement of the 373rd Infantry Regiment in the Organized Reserves and then moving the unit to its new Headquarters in San Juan. In 1967, Headquarters and Headquarters Company 166th General Support Group was activated at San Juan, and within three years became the 166th Support Group and relocated to Puerto Rivo.
The Army placed the 166th Support Group directly under United States First Army in December 1973, and in 1974 it was given full mission control of all U.S. Army Reserve units in both Puerto Rico and assumed the missions and functions of a major U.S. Army Reserve Command. Since 1990, Soldiers under 1st Mission Support Command have been activated and deployed in support of the Persian Gulf War and Operations Joint Guard, Noble Eagle, Iraqi Freedom, and Enduring Freedom, living up to their motto of “Sentries of Peace.”
Featuring the .turreted battlements of Morro Castle, a famous historic landmark in San Juan, the insignia of 1st Mission Command has a convoluted history that we trace back only to 1990 when it was designated for U.S. Army Reserve Forces Puerto Rico. It was cancelled and then reauthorized for the 65th U.S. Army Reserve Command in 1992, then redesignated for the 65th Regional Support Command in 1998. The Regional Support Command was redesignated as the 65th Regional Readiness Command in 2003, then redesignated back to the 166th Support Group in 2007. It was redesignated for the 1st Support Command on 7 February 2008.
In December 2018, the Army Reserve Caribbean Geographical Command was established, with all Army Reserve wearing the Garita patch worn by the 65th Infantry Regiment in the Korean War.