King was promoted colonel on 10 December 1962, and then commanded the 11th Infantry Brigade group, based at Minden in Germany, from 1963–65. He became Military Adviser (Overseas Equipment) in the Ministry of Defence in 1965, and was promoted brigadier on 17 December 1965, continuing in the same role for the rest of 1966. On 1 January 1967 he was promoted major general and appointed Director, Land/Air Warfare, and Commandant of the Army Air Corps. On 5 August 1968 he became Director, Military Assistance Overseas, back at the Ministry of Defence, stepping down on 15 May 1969. He was then appointed Commandant of the Royal Military College of Science on 10 July 1969, and in the 1971 New Year Honours was appointed a Companion of the Order of the Bath (CB), he relinquished the post on 1 October 1971. It was widely expected that given his technical background he would become Master-General of the Ordnance; but his command experience was equally strong and as a result, on promotion to lieutenant general on 1 November 1971 (with seniority from 2 February 1971), he was appointed General Officer Commanding-in-Chief, Army Strategic Command, and in the 1972 New Year Honours was promoted to Knight Commander of the Order of the Bath (KCB). The home commands were abolished in 1972, and so on 1 April King became Deputy Commander-in-Chief UK Land Forces, subordinate to General Sir Basil Eugster, the Commander-in-Chief, he stepped down on 15 January 1973. On 1 February 1973 King succeeded Sir Harry Tuzo as GOC Northern Ireland and Director of Operations. This was the worst period of the Troubles, nearly 12,000 bombing and shooting incidents had occurred the year before King's appointment, but by the end of his period in command, the figure was down to just under 2,500 a year. His obituary in "The Times" states that he "was regarded by many as the best and most successful Director of Operations in Northern Ireland in the 1970s and 1980s", though it also notes that he himself would be happy to attribute much of the preparatory work to Tuzo (who has been described in similar terms). His success was attributable to a number of factors: he regularly visited the troops on the ground which gave him a good picture of the difficulties faced in particular areas; once a unit or commander had proved itself, he was happy to delegate considerable authority, in particular to his immediate subordinate, Commander Land Forces (Sir) Peter Leng; he had a good relationship with the Secretary of State for Northern Ireland, Merlyn Rees, who said of King "You have never played at politics and I have never played at being a soldier; that's why we have got on so well."