Philosophers have disagreed on the role of morality in war. Some, such as Augustine, say that morality is irrelevant to war, and others insist that it is essential to its proper functioning. Regardless of the position, a war involves death, the threat of death, and the potential for devastation.

Although the legitimacy of war is disputed in law, it can be justified in some situations. For example, if a nation states that it is waging war because of a “just cause” (i.e., to protect its own citizens), it may be justified in the interest of peace. However, the legitimacy of the legal authority must outweigh the negative effects. In other words, war should be a last resort.

Theories about war have evolved over the past three centuries. After the wars of religion, wars became primarily a matter of interests between sovereigns. As the art of maneuver became increasingly important, the definition of war became more precise and stratified. The French Revolution, meanwhile, increased the size of forces and shifted the goals of war to the ideals of revolution.

The Geneva Conventions are a series of international treaties designed to protect the rights of civilians, prisoners, and non-combatants. They were negotiated in Geneva, Switzerland, between 1864 and 1977. The first and second Geneva Conventions deal with the treatment of sick and wounded soldiers, sailors, and civilians. The third and fourth Geneva Conventions cover prisoners of war and people in occupied territories. The first Geneva Convention states that armies must provide medical care for the injured on the battlefield.

International humanitarian law is also important in determining guilt in war. Under international humanitarian law, if a country is suspected of war crimes, it must investigate the allegations. For example, the International Criminal Tribunal for the Former Yugoslavia (ICTY) was instrumental in prosecuting war criminals during the Bosnian war in the 1990s. The United Nations Security Council has also imposed sanctions on countries that violate the rules of war.

War has huge psychological and physical consequences for the people involved. Besides deaths in the conflict, wars can result in the destruction of social infrastructure and a breakdown of trust in human relations. Moreover, women and children are especially vulnerable to sexual violence and abuse. If women are not protected, they can be killed or raped by soldiers in the conflict zone.

There are two types of wars: civil war and asymmetric war. A civil war is a conflict between forces from the same nation or political entity. An asymmetric war, on the other hand, is a conflict between two drastically different populations. In these cases, guerrilla tactics are often used to overcome gaps in technology and force size.

A major challenge to war crimes is the ability to prosecute war criminals. Until recently, war crimes were considered part of war and punishment depended on who won the war. In many cases, commanders and politicians were spared from punishment. However, politicians who lost the war were summarily executed. This is because the political and military leaders did not take criminal responsibility for the actions of their troops and states.