In spite of strained relationships with the British, Nkrumah had been able to get Queen Elizabeth II to visit Ghana in 1961. As late as 1964, Lord Mountbatten, a hero of the First and Second World Wars and then Britain's chief of defense staff, visited Ghana, which was an indication of how important British military training remained to the erstwhile colony. Ghana also remained a member of the Commonwealth, but in 1965, when the white Rhodesians unilaterally declared themselves independent from Great Britain, this link to the West also began to weaken. Ghana took a leading role in criticizing Britain for not preventing this seizure of power by the white minority. Nkrumah called for military intervention, and with the example of the Congo in 1960 still fresh, he hoped that Ghanaian forces would play a prominent role. Eventually, under pressure from other OAU members, Ghana was forced to break diplomatic relations with Great Britain. However, even after the latter's diplomats left, a military mission remained that included a British brigadier. The possibility of military involvement in Rhodesia was most unwelcome to the demoralized Ghanaian military. It seemed as if the President's Own Guard Regiment (POGR) was going to succeed the regular military, which was suspect and being starved for funds. Even as Nkrumah was holding out the possibility of offensive operations in Rhodesia, he was forcing into retirement the army's most senior officers. It was this action more than any other, according to then Major A. A. Afrifa, that led to the military-police coup that overthrew Nkrumah on February 24, 1966. Nkrumah had welcomed the military coup that took place in Nigeria a few weeks before and had tried to strengthen the position of the more radical members of the military government that took power. Little did he realize how soon his own demise was to come at the hands of his own military. When this happened, Nkrumah was out of the country in China, where he had gone on a mission initiated by Ghana's fellow Commonwealth nations to end the war in Vietnam. As was the case for so many of Nkrumah's projects, it was totally unrealistic mission, since neither the Americans nor the North Vietnamese were interested in following the lead of a bankrupt African nation. The Americans were convinced that Nkrumah's collapse was imminent. They had refused to supply badly needed food aid. The North Vietnamese felt the tide of war was going their way and there was no need to negotiate. Nkrumah's own staff was dead set against the mission, but his determination to go ahead with it was an indication of how desperate the Osagyefo had become for a diplomatic triumph. The coup itself was welcomed in Ghana with far more enthusiasm than had been the case for independence. Only the Presidential Guard put up a brief resistance, and within 24 hours the coup was over. Nkrumah's statue outside Parliament House, which proclaimed him the founder of the nation, was battered to the ground and smashed into pieces. The bars were jammed with celebrants the night after the coup. There were demonstrations of support for the new rulers, who styled themselves the National Liberation Council (NLC). Even members of the 74-man delegation that had accompanied Nkrumah to China deserted their former leader. Foreign Minister Quaison-Sackey, who Nkrumah had sent to protest the seating of the new Ghanaian government's mission at the OAU meeting in Addis Ababa, flew instead to Accra, where he pledged his loyalty to the new government. The prisons emptied of Nkrumah's detainees and began to fill with new political prisoners. The CPP, with its 2-million strong membership and 500,000 militants, offered no resistance, and the party allowed itself to be disbanded by a single radio announcement. As for Nkrumah, his friend and sometimes rival President Sekou Toure offered him refuge and made him the honorary co-president of Guinea. He was to spend five years in his new home engaged in writing projects and cultivating roses while waiting for the people of Ghana to call him back. Eventually, stricken with cancer, he was flown to a clinic in Bucharest, where he died on April 27, 1972.
Undoubtedly the most important indication of Nkrumah's enduring stature is how much better he has done in retrospect than those who overthrew and succeeded him. He left a stamp on Ghanaian history that continues, long after his death, to fascinate and inspire many of his countrymen as well as people all over the world of African descent. In the following chapters we shall see just how much his countrymen continue to "render homage" to his "immortal memory," even to the point that his weakness and failures have been largely forgotten.81 Ghana pioneered the road to independence for much of Africa. Nkrumah's violent removal from office also unfortunately brought Ghana into line with what was emerging as the dominant trend in much of the continent—the military intervention into politics.
From “The history of Ghana” – Roger S. Gocking - ISBN 0-313-31894-8
Additional reading:
http://www.the-latest.com/anniversary-hidden-cia-coup-toppled-nkrumah
https://amp.pulse.com.gh/news/1966-ghana-coup-four-major-players-in-the-1966-coup-id4721558.html