Background
He was born in Thornhill, Upper Canada, the son of Edward G. O'Brien, an immigrant from Ireland, and was educated at Upper Canada College.
politician member of the House of Commons of Canada
He was born in Thornhill, Upper Canada, the son of Edward G. O'Brien, an immigrant from Ireland, and was educated at Upper Canada College.
He represented Muskoka and Parry Sound in the Canadian House of Commons from 1882 to 1896 as a Conservative member. He was called to the Ontario bar in 1874. O'Brien was an unsuccessful candidate for a seat in the House of Commons in 1878.
He was a lieutenant-colonel in the militia and commanded a regiment during the North-West Rebellion of 1885. He was defeated when he ran for reelection in 1896.