In September 1952, Dwyer was ordered to Korea. During the Korean War, he served as executive officer of the USMC Advisory Groupto the 1st Korean Marine Corps Regiment; As S-3, 5th Marines; Assistant G-3 and Assistant G-3 for the 1st Marine Division.
After Korea
Dwyer returned to the States in August 1953 and served for two years as an aide to the Joint Chiefs of Staff. In December 1955, he was promoted to lieutenant colonel. , 1969. From 1955 to 1958, Dwyer served as an instructor at Marine Corps Schools, Ouantico, followed by a tour of duty in London on the staff of CINCNELM/CINCUSNAVEUR, After attending the Armed Forces Staff College, he joined the 2nd Marine Division and assumed command of the 2nd Battalion, 6th Marines as Assistant Force Marine Officer, Amphibious Plans and operations officer. While in this assignment he participated in contingency operations in Lebanon in 1958. He was deployed to the U.S. 6th Fleet as commander, Task Force 62 and later was deployed as the commanding officer, Battalion Landing Team 2/6 during the Cuban contingency operations. In December 1962, LtCol Dwyer became Asst G-1 of the 2nd Marine Division. Ordered overseas in June 1963, he joined the 1st Marine Aircraft Wing in Japan as Assistant G-1, later becoming G-1. While serving in this capacity, he was promoted to colonel in July 1964. He returned to U.S. in July 1964. From September 1, 1964, to late January 1965, was assigned as head, Western Region Team, Joint Plans Group, DC/s, Plans and Programs, at Headquarters Marine Corps. From February 1965 to June 1967, Dwyer served as USMC Aide to the Secretary of the Navy. In May 1968, Col Dwyer graduated from the National War College, Washington, D.C..
Vietnam War
In June 1968, Dwyer reported to the Republic of Vietnam, and was assigned as the CO, 1st Marines, 1st Marine Division, FMF. He was promoted to brigadier general on August 14, 1968, and subsequently served as assistant division commander, 1st Marine Division; Commanding General Task Force Yankee, 1st Marine Division; and finally as G-3, III Marine Amphibious Force.
Post-Vietnam
Following his return to the States in late June 1969, Dwyer commanded the 5th Marine Division until it was deactivated in December 1969. He then commanded the 5th Marine Expeditionary Brigade, which was redesignated the 5th Marine Amphibious Brigade on September 1, 1967. On April 30, 1971, Dwyer became commanding general of 1st Marine Division at Camp Pendleton, California, and also assumed additional duties as commanding general of I Marine Amphibious Force. Dwyer was promoted to major general in August 1971. After leaving the 1st Marine Division on August 10, 1972, he served as deputy director, Joint Staff, Joint Chiefs of Staff, Washington, D.C., until February 1973, when he became deputy commander, Fleet Marine Force, Atlantic. He received a second gold star in lieu of a third award of the Legion of Merit upon his retirement on September 1, 1974. Dwyer died on October 8, 2001, at the age of 82.