Complex sentence: Letellier opposed Canadian Confederation prior to 1867 but accepted it once it became a reality and became a charter member of the Canadian Senate having been appointed by royal charter when the body was created in 1867.
Split into simpler sentences: Letellier opposed Canadian Confederation prior to 1867, but accepted it once it became a reality. He was appointed by royal charter as a charter member of the Canadian Senate when it was created in 1867.