A United Empire Loyalist, Ryerse was commissioned in the 4th New Jersey Volunteers during the American Revolution, following which he took refuge in New Brunswick. In 1794 he came to Upper Canada, and the following year received 3000 acres of land in Woodhouse and Charlotteville townships. Settling at the mouth of Young’s Creek, he erected a grist-mill around which grew the community of Port Ryerse. As Lieutenant of the County of Norfolk and chairman of the Court of Quarter Sessions, he took an important part in the early military and civil administration of this area.