Born in Montréal, Girouard was educated at Royal Military College, Kingston, commissioned in the Royal Engineers in 1888, and appointed to the Royal Arsenal Railways at Woolwich. Charged in 1896 with construction of the Wadi Halfa - Khartoum Railway, he was later director of railways in South Africa and as high commissioner in Northern Nigeria superintended the building of a line to Kano. Governor of Northern Nigeria (1908-9), of East Africa (1909-12), and director general of munitions supply in the British government (1915-16), he also wrote several books on the strategic importance of railways.