Complex sentence: In 1046, Leofric became the Bishop of Crediton: following his appointment he decided that the see should be moved to the larger, more culturally significant and defensible walled town of Exeter.
Split into simpler sentences: In 1046, Leofric became the Bishop of Crediton. Following his appointment he decided that the see should be moved to the larger and more culturally significant and defensible walled town of Exeter.