In 1940, after graduating from Oxford, Greatbatch was appointed to the Colonial Service and became a district officer in Northern Nigeria. However, during the Second World War he served from 1940 to 1945 with the Royal West African Frontier Force, seeing active service in the Burma Campaign, during which he was mentioned in despatches. After rising to the rank of Major, in 1945 he returned to the Colonial Service in Northern Nigeria. In 1956, he was promoted to Resident, and in 1957 became Secretary to the Governor and the Executive Council. In 1958 he was promoted again to Senior Resident in Kano, after which he was Secretary to the Premier of Northern Nigeria.[2] The Federation of Nigeria gained independence from Britain in 1960.
Greatbatch oversaw the forced deportation of the Chagossians between 1968 and 1973. He and his subordinate, John Rawling Todd, were accused of ordering the island's dog population of 1,000 to be gassed as a means of intimidating the Chagossians before deportation.[3] The deportation was carried out at the request of the United States government in order to construct a military base on Diego Garcia.[4]