 In 1899 he succeeded his father as surgeon to the 89th Regiment but, a few months later, joined the Second (Special Service) Battalion of The Royal Canadian Regiment with the rank of major and saw service in the South African War.For his service in the war, he was appointed a Companion of the Distinguished Service Order (DSO) in the October 1902 South African Honours list.With the end of his tour of duty in South Africa in 1900, Fiset interned at the Nose and Throat Hospital in London and L'Hôpital Saint-Antoine in Paris.