Bob Denniston was born on June 12, 1920, in La Paz, Bolivia. He graduated from law school at the University of Alabama and began practicing law in Mobile, Alabama, in June 1941. He was commissioned an Ensign in the U.S. Navy on January 2, 1942, went on active duty beginning January 21, 1942, and served as a coding officer before going to sea as Executive Officer of the submarine chaser SC-645 in September 1942. He served as Commanding Officer of SC-645 from November 1942 to june 1943. LT Denniston next served as anti-submarine officer aboard the destroyer escort USS Weber (DE-675) in the North Atlantic and the Pacific from June 1943 to July 1945, followed by service as Executive Officer aboard the high-speed transport USS Tatum (APD-81) in the Pacific Theater from July 1945 until he was released from active duty on July 3, 1946. He then resumed his law practice in Mobile, but was recalled to active duty during the Korean War, on March 23, 1951. LCDR Denniston served as Executive Officer of the destroyer USS Barton (DD-722) from June 1951 to December 1952, serving in waters off of North Korea from May to September 1952. He left active duty on January 23, 1953, and retired from the Naval Reserve as a Commander on August 1, 1967. After his Korean War service, Bob continued his law practice in Mobile, and had still not retired as of 2012.

His Navy Commendation Medal w/Valor Citation reads:

For meritorious service as Executive Officer and Navigator of the U.S.S. BARTON, during operations against the enemy in the Korean Theatre from 18 June 1952 to 19 October 1952. During this period, Lieutenant Commander Denniston consistently displayed outstanding leadership and exceptional professional competence in maintaining the ship in a high state of battle readiness. When the BARTON was struck by an enemy shell, on 10 August 1952, starting a fire and causing secondary explosions among ready ammunition, Lieutenant Commander Denniston, with complete disregard for his own personal safety, immediately proceeded to the scene of the hit and successfully directed efforts to subdue the blaze and control the damage. On 16 September 1952, the BARTON struck and exploded a drifting enemy mine. The blast ripped a large hole in the forward fireroom, flooding it instantly, killing the watch there, and causing widespread damage. Lieutenant Commander Denniston made on immediate survey of the damaged area and initiated prompt and effective measures to determine personnel casualties and restore or improvise disrupted communication and ship control circuits. His courageous leadership and steadfast devotion to duty were at all times in keeping with the highest traditions of the United States Naval Service.

The Commendation Ribbon with Combat Distinguishing Device is authorized.