Complex sentence: William was elected to the see of Canterbury as a compromise candidate in 1123, succeeding Ralph d'Escures, who had employed him as a chaplain, the first canon to become an archbishop in England.
Split into simpler sentences: William was elected to the see of Canterbury as a compromise candidate in 1123, succeeding Ralph d'Escures, who had employed him as a chaplain. He was the first canon to become an archbishop in England.