Lieutenant Commander MacKenzie was killed in action 15 March 1943 when three Imperial Japanese Navy destroyers sank Triton in waters just north of the Admiralty Islands.

After shakedown off Cuba, MacKenzie returned to Boston, Massachusetts on 15 September 1945 and subsequently participated in the Navy Day celebrations on 27 October at Savannah, Georgia She served with the Operational Development Force at Norfolk, Virginia, her home port, and conducted training exercises and escort duties along the Atlantic seaboard until sailing on 5 January 1948 on a goodwill tour to Buenos Aires, Argentina.

MacKenzie returned to Norfolk on 9 February after these duties as a "steel grey diplomat" and continued peacetime operations, highlighted by a Midshipman cruise June to July 1948 to Portugal, Italy, North Africa, and Cuba.

In October 1948 the destroyer sailed for the Near East, where she supported the United Nations Palestine Patrol and the allied occupation of Trieste, returning to Newport, Rhode Island for Christmas.

During her first tour in Korea, from 26 July 1950 to 30 January 1951, she screened attack carriers during strikes on North Korean targets and provided close support for advancing Allied armies.

George K. MacKenzie provided antisubmarine screening and fired several important bombardment missions at Wonsan Harbor, 16 to 17 January and again 23 February to 21 March 1953 in support of United Nations forces.

She lent effective fire support to troops in the vicinity of Suwon Dan from 15 to 19 April 1953 in company with USS Los Angeles and demolished sections of the enemy's railroad along the eastern coast of Korea in May.

In 1961 MacKenzie sailed from Subic Bay, P.I., on 23 March to rendezvous with carriers Midway (CV-41) and Lexington (CV-16) in the South China Sea to act during the Laos crisis as a powerful on-the-spot force, if needed.

In July 1970 the entire squadron returned together to San Diego with homeward-bound pennants flying, to be greeted at the pier by Governor Reagan, Senator Murphy, the COMCRUDESPAC Band and several hundred family members and well-wishers.

George K. MacKenzie was deployed to Vietnam in 1971 again with the mission of fleet defense and shore bombardment with other vessels, including the cruiser Oklahoma City (CLG-5) USS Newport News} In the Spring of 1972 she participated in Operation Freedom Train conducting shore bombardment of targets in North Vietnam and in operation Linebacker 1 and Linebacker 2 it may be noted here that during this arduous tour of duty she fired 16,549 rounds of 5"/38 ammunition.