How did Hugo Grotius’s ideas aim to reduce violence during wars?

Hugo Grotius, often called the "father of international law," sought to minimize bloodshed and violence in warfare through his seminal work, De Jure Belli ac Pacis (1625). His approach was rooted in the following strategies:123

• Multilayered Normative Framework: Grotius constructed a system of jurisprudentia that combined natural law—which he argued was valid regardless of religious belief—with religious norms from the Old Testament and New Testament. He utilized these layers to restrain both the decision to go to war and the conduct of violence during combat.3
• Limiting Just Causes: He argued that war should only be permitted for just causes, such as defense or the restitution of property, effectively limiting war to situations akin to legal litigation.3
• Humanitarian Principles: Grotius explored fundamental principles regarding the humane treatment of war victims, providing an early framework for protecting those unable to defend themselves.34
• Utility as a Last Resort: When normative arguments failed to discourage leaders from violence, he employed arguments based on utility to advocate for restraint.3