During the American Revolution, he broke with Quaker doctrines against violence and fought with the British and became a member of a company of soldiers led by Peter Van Alstine.
After the war, he settled in Adolphustown Township in Upper Canada and later joined the Church of England.
He was appointed justice of the peace in the Midland District in 1800 and also represented Lennox and Addington in the Legislative Assembly of Upper Canada from 1804 to 1812.
From 1802 to 1824, Dorland operated a ferry between Adolphustown and Van Alstine's Mills (Glenora) in Prince Edward County.
His brother Philip had been elected to the 1st Parliament of Upper Canada but was unseated because, as a practicing Quaker, he refused to take the oath of office.