Military intelligence
The Chinese general and strategist Sun Tzu (544 BC – 496 BC) wrote about the importance of military intelligence. In his book The Art of War he wrote: "If you know both yourself and your enemy you can win a hundred battles without jeopardy." He emphasized the importance of using spies to learn an enemy's strength and what they were doing. He also wrote: "All warfare is based on deception". What he meant was war can even be avoided if you feed your enemy enough bad information. This is also called counterintelligence. Ancient Rome depended heavily on intelligence information to rule it's empire.