īe subtle! be subtle! and use your spies for every kind of business. Without subtle ingenuity of mind, one cannot make certain of the truth of their reports. They cannot be properly managed without benevolence and straightforwardness. Spies cannot be usefully employed without a certain intuitive sagacity. In no other business should greater secrecy be preserved. Hence it is that which none in the whole army are more intimate relations to be maintained than with spies. SURVIVING SPIES, finally, are those who bring back news from the enemy's camp. Having DOOMED SPIES, doing certain things openly for purposes of deception, and allowing our spies to know of them and report them to the enemy. Having CONVERTED SPIES, getting hold of the enemy's spies and using them for our own purposes. Having INWARD SPIES, making use of officials of the enemy. Having LOCAL SPIES means employing the services of the inhabitants of a district. This is called 'divine manipulation of the threads.' It is the sovereign's most precious faculty. When these five kinds of spy are all at work, none can discover the secret system. Hence the use of spies, of whom there are five classes: (1) Local spies (2) inward spies (3) converted spies (4) doomed spies (5) surviving spies. Knowledge of the enemy's dispositions can only be obtained from other men. Now this foreknowledge cannot be elicited from spirits it cannot be obtained inductively from experience, nor by any deductive calculation.

Thus, what enables the wise sovereign and the good general to strike and conquer, and achieve things beyond the reach of ordinary men, is FOREKNOWLEDGE. One who acts thus is no leader of men, no present help to his sovereign, no master of victory. This being so, to remain in ignorance of the enemy's condition simply because one grudges the outlay of a hundred ounces of silver in honors and emoluments, is the height of inhumanity. Hostile armies may face each other for years, striving for the victory which is decided in a single day. As many as seven hundred thousand families will be impeded in their labor. There will be commotion at home and abroad, and men will drop down exhausted on the highways. The daily expenditure will amount to a thousand ounces of silver.

Sun Tzu said: Raising a host of a hundred thousand men and marching them great distances entails heavy loss on the people and a drain on the resources of the State.

Did war world 1 have a spy network