Complex sentence: Siward was a monk at Glastonbury until he was appointed Abbot of Abingdon in 1030; he was made Bishop of St Martins in 1044, but resigned and died in 1048 (Kelly 2000).
Split into simpler sentences: Siward was a monk at Glastonbury until he was appointed Abbot of Abingdon in 1030. He was made Bishop of St Martins in 1044, but resigned and died in 1048 (Kelly 2000).