Born in London, Ontario, Walter Sage was educated at the University of Toronto (BA, 1910) and Oxford University, where he obtained his MA in history (1916). He later earned a Ph.D. from Toronto (1925). His first teaching position was at Calgary College in 1913 as a lecturer in history. After teaching there for two years, he went to Queen's University. Sage joined the faculty at the University of British Columbia in 1918 as an assistant professor of history, rising to head the department fourteen years later (1932). He continued serving as a head until his retirement in 1953. He became a leading authority on the history of British Columbia, writing numerous articles and delivering countless addresses on the subject. Sage participated in multiple historical associations accepting the presidency of the British Columbia Historical Association (1939), the Canadian Historical Association (1945), and the American Historical Association (Pacific Coast Branch) (1950). From 1944 he was a member of Canada's Historic Sites and Monuments Board until he died in 1963.