What goal did Hugo Grotius seek to achieve by writing On the Law of War and Peace?

Hugo Grotius wrote On the Law of War and Peace (De Jure Belli ac Pacis) with the primary practical objective of minimizing bloodshed in conflicts. Observing a profound lack of restraint in warfare throughout the Christian world—particularly during the Thirty Years’ War—he sought to construct a general theory of law that would regulate and restrain violence between independent powers.1

To achieve this, Grotius argued for a common law among nations rooted in natural law, which he posited would remain valid even if independent of religion. Recognizing that secular norms alone might not suffice to persuade rulers, he employed a multilayered approach, incorporating elements of Christianity and arguments based on utility to discourage cruelty. Ultimately, he aimed to limit the resort to war to only those instances with just causes, such as defense or the restitution of property, thereby establishing a framework for international conduct.1