Complex sentence: The "Anglo Saxon Chronicle", commissioned at the time of Alfred, was probably written to promote unification (of England), whereas Asser's "The Life of King Alfred" promoted Alfred's achievements and personal qualities.
Split into simpler sentences: The "Anglo Saxon Chronicle", commissioned at the time of Alfred, was probably written to promote unification (of England). Whereas, Asser's "The Life of King Alfred" promoted Alfred's achievements and personal qualities.