This article re-examines King John’s persecution and eventual destruction of his former friend, William de Briouze, a signal example of John’s tyranny on the eve Magna Carta. Approaching the episode from the transnational perspective of the two men involved, the study uncovers the roots of their dispute in King John’s attempts to introduce English-style royal rule to Ireland. Desperate to extract what he could from his insular possessions following the loss of Normandy in 1204, John’s attempts to increase his authority in Ireland provoked a violent response from its greatest magnates in 1207. John lost this lesser-known baronial revolt, but the most prudent of his barons soon came to terms with him. Not so William de Briouze, who, we are to...