Before the American Revolutionary War, he moved to Chatham County, North Carolina.
During the war, he served as a major in the United States Army and was active in suppressing the Tories commanded by David Fanning.
The other legislators from Sullivan County at that time were Colonel Abraham Bledsoe and David Looney.
In 1774, there was a movement to form the state of Franklin from a group of western North Carolina counties.
Cage took a central role in the movement, and was appointed treasurer and elected speaker of the lower house of the first assembly of the provisional state, serving from August 1784 to June 1785.