When Greatbatch arrived in the Seychelles and the British Indian Ocean Territory, the United States and United Kingdom had already begun a process of depopulating
Diego Garcia to build a joint military base there. In a 1966 series of diplomatic cables, two British diplomats had complained that "unfortunately" there were "some few Tarzans or Men Fridays whose origins are obscure" on the islands, and "The United States Government will require the removal of the entire population of the atoll". Greatbatch oversaw this expulsion in his role as BIOT Commissioner. As part of the process, he ordered the islands' dog population to be killed, even before the last of the human residents were removed. Some of these dogs were strays left behind from families previously taken off the islands, but others were pets of families still present. Various methods of killing the dogs were attempted, including shooting and poisoning them, but most efficient method was to lure them into the old coconut furnaces and pipe in exhaust fumes from military vehicles to asphyxiate them. The islanders took this as a method of intimidation to encourage them to leave the islands. In 1971, Greatbatch issued an Immigration Ordinance that banned anyone except British soldiers and officials from entering or staying on the Chagos Archipelago without a permit. By the end of 1973, all Chagossians had been exiled from the islands. Unlike the dogs, Greatbatch ordered that the horses on the islands be saved and moved to Mauritius or the Seychelles. The final boatload of Chagossian exiles had people filling the bottom of the boat, with horses filling the top deck. ==Honours==