The Belgian scholar Ernest Nys (1851-1920), a big name in public international law and legal history, is mainly known for his extensive publications in the Revue de droit international et de législation comparée, often focusing on medieval and early modern doctrine. Yet, Nys was active as a judge and an ad hoc legal adviser, combining his abilities as a traditional continental law-jurist and a legal historian. During World War One, he drafted an impressive manifesto against wartime contributions on movable property designed by the German Occupant. The text combines an intellectual pedigree of political thought with strict legal reasoning on the basis of classics, such as the 1874 Brussels Conference or the 1899 and 1907 Hague Conventions. Finally, Nys’ motivations for an assault on this capital tax, which included a compulsory declaration of personal wealth, can be situated in traditional liberal resistance against state intrusion into the private sphere.