How did mercenary armies influence military legal procedures in the 16th and 17th centuries?

During the 16th and 17th centuries, the prevalence of mercenary armies significantly influenced military legal procedures. Because these forces were composed of diverse national contingents, each group often attempted to apply the supreme commander's articles of war according to its own internal rules of procedure.1

To maintain discipline among these often undisciplined and potentially mutinous troops, commanders relied on the rigorous enforcement of articles of war. The codes established by leaders such as Maurice of Nassau and Gustav II Adolf became highly influential, serving as models for national commanders who later implemented similar systems elsewhere. For instance, these articles formed the basis for military codes in the English Civil Wars and remained the standard on the European continent until the 19th-century codification of military law.12

Ultimately, the need to govern these professional, international forces helped transition military justice from varied, commander-specific practices toward more standardized, formalized systems of discipline.1