I recently went through one of my favorite classic works and picked out some good quotes from The Art of War by Sun Tzu. No, I didn't bother with the totally famous one about "Every battle is won or lost before it's fought" because that little treatise on thumping your enemies is so packed with lesser known statements that deserve notice.
Here's a few examples:
When some are seen advancing and some retreating, it is a lure.
The sight of men whispering together in small knots or speaking in subdued tones points to disaffection amongst the rank and file.
There is no instance of a country having benefited from prolonged warfare.
Visit the full page of Sun Tzu Art of War quotes and use them as needed.