This dissertation examines the different attitudes of soldiers and intellectuals towards the laws of war and the rules of engagement, with a particular focus on defining the enemy. In the past there has been a focus on the broader theories of the laws of war and how they work on paper. This is why studying the attitudes of soldiers who have firsthand experience of the rules of engagement is useful in understanding the moral issues in war. The general attitudes of intellectuals and soldiers towards the laws of war are first examined, relying on the past historiographical work of Michael Walzer and John Fabian Witt. This is followed by an examination of the moral ambiguities generated by war in a historical context, using specific examples from past conflicts. Soldiers’ autobiographies from the War on Terror are a rich source of analysis They reveal how the rules of engagement imposed by the legislators do not necessarily correspond to the soldiers’ perspective on the battlefield which leaves soldiers vulnerable to charges of murder.