Complex sentence: In the early 19th century, reform-minded groups began to form in the British colonies in Canada; from them rose William Lyon Mackenzie, who, along with Louis-Joseph Papineau, was the first prominent proponent of a republican Canada.
Split into simpler sentences: In the early 19th century, reform-minded groups began to form in the British colonies in Canada. From them rose William Lyon Mackenzie, who, along with Louis-Joseph Papineau, was the first prominent proponent of a republican Canada.