Oscar Douglas Skelton was born on July 13, 1878 in Orangeville, Ontario. After a brilliant undergraduate career at Queen's University in Kingston, Ontario, Skelton was awarded his M.A., along with medals for highest standing in Latin and Greek. In 1908, he received his Ph.D. in political economy from the University of Chicago. That same year, Dr. Skelton was named Sir John A. Macdonald Professor of Political and Economic Science at Queen's. Eleven years later, he was named Dean of Arts, a post he held until he resigned from the university in 1925. Dr. Skelton was a prolific scholar, the author of several major books, including biographies of Sir Alexander Tilloch Galt and Sir Wilfrid Laurier.
In 1925, Dr. Skelton accepted Prime Minister W.L. Mackenzie King's offer to succeed Sir Joseph Pope as Under Secretary of State for External Affairs. Until his death, in late January 1941, Dr. Skelton served as the principal adviser to the Prime Minister, sometimes called the "deputy prime minister". To Mackenzie King, his death was "the most serious loss thus far sustained in my public life!" One Canadian historian has described him simply as the most powerful civil servant in Canadian history.
As head of the Department of External Affairs for more than fifteen years, Dr. Skelton helped to define a distinct Canadian foreign policy. He also was responsible for the recruitment of a remarkably able group of officers. Dr. Skelton firmly believed in appointment and promotion by merit and the list of recruits he attracted to Ottawa is an impressive one indeed, highlighted by two Governors-General (Georges Vanier and Jules Léger) and one Prime Minister (Lester B. Pearson) as well as numerous senior mandarins.