Following the war, he served for three and one-half years as Managing Editor of the Marine Corps Gazette, then completed the Amphibious Warfare School, Junior Course, Quantico, in 1950.

Carbine rifles from his office, left behind after the United States interrupted formal diplomatic relations, were used in the assassination of Rafael Trujillo according to the Church Committee.

Prior to returning to the Dominican Republic in September 1961 as U.S. Military Liaison Officer, U.S. Embassy, Santo Domingo, he was assigned as senior editor, Publications Group, Marine Corps Schools, Quantico.

In January 1962, he joined the Strategic Plans Section, G-3 Division at Headquarters Marine Corps, and in July 1963 was promoted to colonel.

He went on the retired list on July 1, 1972, but continued on active duty without interruption of service as director of Marine Corps History and Museums.

In late October 1978, he returned as a Civil Service employee to his previous position as director of Marine Corps History and Museums.

[6][7] In May 2013, construction began for the Senator John W. Warner Center for Advanced Military Studies at Marine Corps University in Quantico, Virginia.

A portion of this facility will house the Brigadier General Edwin H. Simmons Center for Marine Corps History.

The Simmons Center will consolidate resources from the Marine Corps History Division and the Archives and Special Collections Branch, currently held in three locations, into one facility.