In the ancient era, military science started from records on the art of war rather than the science of war. Herodotus and Thucydides wrote the history of the Persian war and Peloponnesian wars. About the same time, Sun Tzu, a strategist in ancient China, wrote "The Art of War". This book showed that war is a serious way for the life and death of nations and surprise is important in the art of war. After the age of the Roman empire, Flavius Vegetius Renatus wrote Roman military theory in his book called "On Military Affairs". Vegetius noted Roman military power was based on discipline, which makes military organizations organized. The Roman way of war that Vegetius recorded had historical influences on military minds of people on Europe for a long time.