Complex sentence: On July 12,1876 he would be appointed District Magistrate in the County and hold that position until he was appointed to the Northwest Territories Council on September 28,1883 replacing Matthew Ryan.
Split into simpler sentences: On July 12,1876 he was appointed District Magistrate in the County and held that position until 1883. On September 28,1883, Rouleau was appointed to the Northwest Territories Council where he replaced Matthew Ryan.