His later career was almost entirely concerned with South and central Africa. He went through the Siege of Kimberley in the Boer War with Rhodes, accompanied by his wife. After Rhodes' death in 1902, Maguire carried on his work as a businessman, in the British South Africa Company, as a director of the Consolidated Gold Fields of South Africa, and particularly in the development of the Rhodesian railway system of which he was chairman for many years.