Chadwick was an Anglican Church History scholar, whose writings helped introduce me (and others I am sure) to the Church Fathers. His knowledge of Church History was quite amazing, and his book The Early Church made learning about the Fathers exciting. An Anglican priest friend of mine once told me that Chadwick would read in the bathroom, only unlike most of us, he was reading (and correcting) Greek grammars.
May perpetual light shine upon him. May he rest in peace.