Espionage plays a big role in our history and there are many examples that show it. The importance of espionage in military affairs has been recognized since the beginning of recorded history. The Egyptians had a well-developed secret service, and spying and subversion are mentioned in the Iliad and in the Bible. The ancient Chinese treatise (c.500 B.C.) on the art of war devotes much attention to deception and intelligence gathering, arguing that all war is based on deception. In the Middle Ages, political espionage became important. Joan of Arc was betrayed by Bishop Pierre Cauchon of Beauvais, a spy in the pay of the English, and Sir Francis Walsingham developed an efficient political spy system for Elizabeth I. With the growth of the modern national state, systematized espionage became a fundamental part of government in most countries. Joseph Fouché is credited with developing the first modern political espionage system, and Frederick II of Prussia is regarded as the founder of modern military espionage. During the American Revolution, Nathan Hale and Benedict Arnold achieved fame as spies, and there was considerable use of spies on both sides during the U.S. Civil War.
By World War I, all the great powers except the United States had elaborate civilian espionage systems and all national military establishments had intelligence units. To protect the country against foreign agents, the U.S. Congress passed the Espionage Statute of 1917. Mata Hari, who obtained information for Germany by seducing French officials, was the most noted espionage agent of World War I. Germany and Japan established elaborate espionage nets in the years preceding World War II. In 1942 the Office of Strategic Services was founded by Gen. William J. Donovan. However, the British system was the keystone of Allied intelligence.
Since World War II, espionage activity has enlarged considerably, much of it growing