Fairfield was born in Pepperellborough, Massachusetts (now Saco, Maine) and attended the schools of York County.

After serving in the War of 1812, he pursued a business career before deciding to become an attorney, and after in the office of an established lawyer and judge, Fairfield attained admission to the bar in 1826.

[1] Fairfield is known to have served on the crew of a privateer during the War of 1812, which led to the nickname "Sailor Boy", but the exact circumstances of his wartime service are not known.

[1] He studied law in the office of attorney and judge Ether Shepley, and was admitted to the bar in 1826.

[1] Fairfield practiced Saco and Biddeford in partnership with George Thacher, and specialized in courtroom pleadings and trials.

[9] In insisting on an investigation, Fairfield broke with the custom of the time, largely favored by pro-slavery Southern members, of not referring to private "affairs of honor" on the House floor.

[11] During Fairfield's governorship, the Aroostook War erupted as the U.S. and Great Britain continued a dispute over the boundary between Maine and New Brunswick, Canada.

[5] When he sought treatment on this occasion, his doctor punctured the skin around his knees to drain built-up fluid, then injected a copper sulfate solution, which was thought at the time to provide relief of the pain and swelling associated with rheumatism.

[5] The doctor did not remove the solution before it was absorbed into Fairfield's circulatory system, and intense pain, paralysis and death resulted.