In 1960, Bristow Helicopters chose to enter the African market via the acquisition of crop-spraying specialist "Fison-Airwork", which had also operated in locations in Central America and the UK. Bristow opted to discontinue crop-spraying activities in favour of focusing on oil exploration work in Nigeria on behalf of Shell; by the start of the Biafran War in 1967, the company had a fleet of 11 helicopters committed the Nigerian oil exploration effort, based at Port Harcourt. Early on in the conflict, Bristow helped to evacuate oil workers in the region to the safety of Fernando Po; despite the risks, Bristow maintained its Nigerian operations throughout the three years of war via a reduced presence in Lagos and Warri. This decision to remain gave the company a head-start on rivals as oil companies returned to the region after the war's end. Throughout much of 1970s, Nigeria functioned as Bristow's biggest profit centre; it continued to grow through the decade via contracts from Shell, Mobil, Texaco and other companies.