The 2nd Aviation Group was formed at Naval Air Station San Diego in August 1922.
 They were redesignated Aircraft Squadrons, West Coast Expeditionary Force in July 1926.
 January 8, 1934 saw another name change, this time to Aircraft Two, Fleet Marine Force.
 On May 1, 1939, they were redesignated again to the 2nd Marine Aircraft Group.
 The group was sent overseas to Marine Corps Air Station Ewa, Hawaii in January 1941.
 There they consolidated with the headquarters of the 2nd Marine Aircraft Wing July 10, 1941, and less than a month later they were redesignated Marine Aircraft Group 21.
The 2nd Aviation Group was formed at Naval Air Station San Diego in August 1922.  They were redesignated Aircraft Squadrons, West Coast Expeditionary Force in July 1926.  January 8, 1934 saw another name change, this time to Aircraft Two, Fleet Marine Force.  On May 1, 1939, they were redesignated again to the 2nd Marine Aircraft Group.  The group was sent overseas to Marine Corps Air Station Ewa, Hawaii in January 1941.  There they consolidated with the headquarters of the 2nd Marine Aircraft Wing July 10, 1941, and less than a month later they were redesignated Marine Aircraft Group 21.
Marine Aviation Training Support Group 21