["Journal of Historical Sociology, Volume 34, Issue 3, Page 479-490, September 2021. ", "\nAbstract\nBandits have been popular ‘heroic’ individuals throughout history. Many of them also proved to be quite useful figures, allowing interested parties to fill in gaps in their capacities on the quick by way of co‐opting them. Such ‘interested parties’ even included kings, whose authority still was a rather limited one. A particularly glaring gap in their authority existed at sea: keeping a fleet at the ready was quite expensive, and affordable only for a few rich exceptions. Everyone else had to make use of naval mercenaries–pirates with a license. One of the most illustrious medieval examples of such maritime entrepreneurs is Eustace the Monk. His colourful life includes being a monk, the seneschal of the Count of Boulogne, a bandit and pirate after he fell out with the count, and finally naval mercenary first for King John of England, then for King Philip Augustus of France. This contribution focuses on Eustace the Monk's maritime career. It will do so by assessing the political constellation and culture of his days which made it possible in the first place.\n"]