Although he participated in the Québec Conference, it was as premier of Ontario that Sir Oliver Mowat helped define the relationship between the provinces and the federal government. He was a champion of provincial rights and fought more than one battle with Canadian Prime Minister John A. Macdonald on this front.
Ironically, Oliver Mowat articled with John A. Macdonald. Given his acquaintances and circles, he should have been a member of the Conservative Party, but his mistrust of George-Étienne Cartier and, more so, of John A. Macdonald made him lean toward the reformers. Throughout his political career, he would advocate the principle of rep by pop.
Oliver Mowat sat in the Legislative Assembly as a reformer from 1858 to 1864. He was considered George Brown's right-hand man in the Assembly. He was secretary of the province in the Brown-Dorion Cabinet of 1858 (which lasted only two days) and postmaster general in the Sandfield Macdonald-Dorion Cabinet from 1863 to 1864, as well as in the Great Coalition of 1864. In 1864, Oliver Mowat signed George Brown's report on proposed changes to the Canadian political system.
Also in 1864, Oliver Mowat was appointed vice-chancellor of Ontario, an office he held until 1872 when he became premier of the province. He remained premier of Ontario until 1896, at which time he was named senator. He was minister of justice in Ottawa for one year, and in 1897, he was appointed lieutenant-governor of Ontario.
Romney, Paul. "Mowat, Sir Oliver." Dictionnaire biographique du Canada. Vol. XIII. Québec: Presses de l'Université Laval, 1994. P. 787-807.
Swainson, Donald. "Mowat, Sir Oliver." The 1999 Canadian encyclopedia: world edition. Toronto: McClelland and Stewart, 1998.