This article examines the emergence and structuring of courts-martial in France and England between the 1630s and the 1660s. It situates them within the broader context of the consolidation of the modern state, the professionalization of armies, and the development of bureaucratic administrations. It shows that these collegiate courts gradually replaced earlier forms of military justice exercised by provosts, captains, and high courts such as the French Connétablie and the English Court of Chivalry. The article highlights how this process formed part of a wider European dynamic characterized by the circulation of administrative and legal models. Between the 1570s and the 1590s, European armies experimented with forms of collective justice to deal with military crimes, in a context marked by intensifying conflicts and growing troop numbers. From the 1630s onwards, these practices tended to stabilize. They were accompanied by the expanding role of civilian actors – intendants in France and the Judge Advocate General in England – reflecting a process of ‘civilianization’ of military justice and a strengthening of central government control over the armed forces. By the 1660s, courts-martial had become institutionalised and were integrated into emerging ministerial structures, such as the French War Department and the English War Office. Their development contributed to the centralisation of the administration, the reinforcement of military discipline, and the consolidation of state authority.