In his The Defender of the Peace, Marsilius of Padua offers a detailed analysis and explanation of human political communities, before going on to attack what he sees as the obstacles to peaceful human coexistence - principally the contemporary papacy. Annabel Brett's authoritative rendition of the Defensor Pacis is the first new translation in English for fifty years. Aimed at the student reader encountering this classic of medieval thought for the first time, this new edition is a scholarly and a pedagogic event of great importance to historians, political theorists, theologians and philosophers at all levels from second-year undergraduate upwards.