In the midst of chaos, there is also opportunity.

No. "In the midst of chaos, there is also opportunity" does not appear in The Art of War. The origin of the English sentence is untraced. The nearest passage is chapter V, section 16, and it argues a different point. The Chinese is 纷纷纭纭，斗乱而不可乱也；浑浑沌沌，形圆而不可败也. Giles describes turmoil in which there may be seeming disorder and yet no real disorder at all, and an array without head or tail that is still proof against defeat.

Read as Giles wrote it, the section is about your own formation, not about a chance hidden in the mess. In the noise of battle you may look confused and still not be confused. The chaos is something you refuse to let into the ranks. Nothing in the section says that chaos contains opportunity. The popular sentence keeps the weather of the lines and replaces the conclusion. If you want V.16, quote Giles on seeming disorder. Leave the opportunity line with no ancient name attached.