A more thorough explanation:

A code of war refers to the legal rules that regulate international armed conflict. These rules can come from various sources such as custom, treaties, scholarly writings, and domestic legislation. One of the earliest known treatises on rules governing the conduct of war was written by Sun Tzu in the 4th century B.C.

• The Geneva Conventions are a set of international treaties that establish the humanitarian rules of war. They provide guidelines for the treatment of prisoners of war, wounded soldiers, and civilians.
• The Hague Conventions are another set of international treaties that regulate the conduct of war. They cover topics such as the use of chemical weapons, the treatment of civilians, and the protection of cultural property.

These examples illustrate how international agreements can establish a code of war that governs the behavior of nations during armed conflict. By following these rules, countries can minimize the harm caused by war and protect the rights of those affected by it.