Berkeley was transferred as Corps Signal Officer to the staff of the V Amphibious Corps under Lieutenant General Harry Schmidt in July 1945 and took part in the Occupation of Japan.
He also received promotion to the rank of colonel in August 1945.
While in Japan, Berkeley was appointed officer in charge of the disposition of enemy material in October 1945, but remained in this capacity only until the end of January 1946, when he relieved Colonel Jack P. Juhan as commanding officer of the 6th Marine Regiment.

Upon his return to the United States at the beginning of April 1946, Berkeley was appointed assistant to the Navy Secretary of the Joint Army-Navy Secretariat within the Office of Secretary of the Navy in Washington, D.C., under James Forrestal.
He was tasked with the review of any paper requiring joint action sent to the Secretary of the Navy.
At the end of January 1947, he was transferred to Buenos Aires, Argentina.
Berkeley was appointed an advisor to the Argentina Marine Corps and to the Argentina Naval War College.
He also helped with the reorganization of the Argentina Marine Corps.

Colonel Berkeley spent next two years in South America and finally returned stateside in May 1949.
He was briefly attached to the Troop Training Unit, Atlantic at Little Creek, Virginia, before he was sent for the senior course at Armed Forces Staff College at Norfolk, Virginia.

He graduated from the course in January 1950 and subsequently assumed duties at the Naval War College in Newport, Rhode Island.
Berkeley served initially as a regular staff member of the Department of Strategy and Tactics, but later was promoted to assistant head of department and then to head of the department.
He was also co-responsible for the preparing of the first-ever Command and Staff course at the junior level for lieutenant commanders and majors.

His next assignment came in May 1953, when he assumed duties as commanding officer of the Marine Barracks, Washington, D.C. and concurrently of the Marine Corps Institute.
The Marines under his command also served as the guard unit for Camp David, the country retreat of the President of the United States, Dwight D. Eisenhower.

Berkeley left for Korea during June 1954 and subsequently assumed duties as chief of staff, 1st Marine Division under Major General Robert E. Hogaboom.
It was too late to see combat, because truce was already in effect.
He spent next several months with the defense of the Korean Demilitarized Zone until his division was ordered stateside in March 1955.
Berkeley was stationed at Camp Pendleton, when he reached the rank of brigadier general on July 1, 1955.

For his new assignment, Berkeley was transferred to Headquarters Marine Corps in Washington, D.C., and appointed assistant chief of staff for personnel.
The billet of Sergeant Major of the Marine Corps was created under his command.
He received his second star, when he was promoted to the rank of major general in July 1958.

Afterwards, Major General Berkeley succeeded George F. Good Jr. as commanding general of Department of the Pacific at San Francisco.
Under his command, the Department of the Pacific was deactivated and Berkeley was transferred to Camp Lejeune at the beginning of November 1959 to assume command of the 2nd Marine Division.
He also commanded Camp Lejeune from November 1961 to July 1963.

The pinnacle of his career came at the beginning of August 1963, when he was promoted to the rank of lieutenant general and appointed Commanding General Fleet Marine Force, Atlantic, with headquarters at Norfolk, Virginia.
In October 1963, Berkeley traveled to Spain in order to arrange joint U.S./Spanish amphibious landing exercise.
He got the agreement of the Spanish Navy Marines Commandant and began the planning, together with Vice Admiral John S. McCain Jr., Commander Amphibious Forces, U.S. Atlantic Fleet.

The landing exercise was named Operation Steel Pike and took place during October and November 1964.
It was the largest peacetime amphibious landing exercise in history, conducted by the United States Navy and Marine Corps.
Berk
Berkeley was transferred as Corps Signal Officer to the staff of the V Amphibious Corps under Lieutenant General Harry Schmidt in July 1945 and took part in the Occupation of Japan. He also received promotion to the rank of colonel in August 1945. While in Japan, Berkeley was appointed officer in charge of the disposition of enemy material in October 1945, but remained in this capacity only until the end of January 1946, when he relieved Colonel Jack P. Juhan as commanding officer of the 6th Marine Regiment.
Upon his return to the United States at the beginning of April 1946, Berkeley was appointed assistant to the Navy Secretary of the Joint Army-Navy Secretariat within the Office of Secretary of the Navy in Washington, D.C., under James Forrestal. He was tasked with the review of any paper requiring joint action sent to the Secretary of the Navy. At the end of January 1947, he was transferred to Buenos Aires, Argentina. Berkeley was appointed an advisor to the Argentina Marine Corps and to the Argentina Naval War College. He also helped with the reorganization of the Argentina Marine Corps.
Colonel Berkeley spent next two years in South America and finally returned stateside in May 1949. He was briefly attached to the Troop Training Unit, Atlantic at Little Creek, Virginia, before he was sent for the senior course at Armed Forces Staff College at Norfolk, Virginia.
He graduated from the course in January 1950 and subsequently assumed duties at the Naval War College in Newport, Rhode Island. Berkeley served initially as a regular staff member of the Department of Strategy and Tactics, but later was promoted to assistant head of department and then to head of the department. He was also co-responsible for the preparing of the first-ever Command and Staff course at the junior level for lieutenant commanders and majors.
His next assignment came in May 1953, when he assumed duties as commanding officer of the Marine Barracks, Washington, D.C. and concurrently of the Marine Corps Institute. The Marines under his command also served as the guard unit for Camp David, the country retreat of the President of the United States, Dwight D. Eisenhower.
Berkeley left for Korea during June 1954 and subsequently assumed duties as chief of staff, 1st Marine Division under Major General Robert E. Hogaboom. It was too late to see combat, because truce was already in effect. He spent next several months with the defense of the Korean Demilitarized Zone until his division was ordered stateside in March 1955. Berkeley was stationed at Camp Pendleton, when he reached the rank of brigadier general on July 1, 1955.
For his new assignment, Berkeley was transferred to Headquarters Marine Corps in Washington, D.C., and appointed assistant chief of staff for personnel. The billet of Sergeant Major of the Marine Corps was created under his command. He received his second star, when he was promoted to the rank of major general in July 1958.
Afterwards, Major General Berkeley succeeded George F. Good Jr. as commanding general of Department of the Pacific at San Francisco. Under his command, the Department of the Pacific was deactivated and Berkeley was transferred to Camp Lejeune at the beginning of November 1959 to assume command of the 2nd Marine Division. He also commanded Camp Lejeune from November 1961 to July 1963.
The pinnacle of his career came at the beginning of August 1963, when he was promoted to the rank of lieutenant general and appointed Commanding General Fleet Marine Force, Atlantic, with headquarters at Norfolk, Virginia. In October 1963, Berkeley traveled to Spain in order to arrange joint U.S./Spanish amphibious landing exercise. He got the agreement of the Spanish Navy Marines Commandant and began the planning, together with Vice Admiral John S. McCain Jr., Commander Amphibious Forces, U.S. Atlantic Fleet.
The landing exercise was named Operation Steel Pike and took place during October and November 1964. It was the largest peacetime amphibious landing exercise in history, conducted by the United States Navy and Marine Corps. Berk
James P. Berkeley