Authoritative history of early castles written by archaeologists and based on their own research. Probably the best book specifically on motte and baileys. Full of fascinating information and insights. Well illustrated with plans and diagrams. Has a gazetteer of the excavations in the British isles which have shown evidence of timber structures.
From the authors’ 1992 Preface: “The purpose of this book is to restore timber castles to their rightful place in the history of fortification; to show that they were not temporary versions of stone castles, but were formidable strongholds which dominated their surrounding landscapes, sometimes for centuries.”