The Art of War by Sun Tzu

I Laying plans contd...

22. If your opponent is of choleric temper, seek to irritate him. Pretend to be weak, that he may grow arrogant.

Notes by Zephyrist:

This relates to emotion in battle. A general needs to use reason to fight his battles not emotion, Sun Tzu would seek to irritate an opponent to get a knee jerk reaction from them. A battle plan born out of emotion or irritation will be weaker than a plan which is logically planned.

If you make your army look weak then the enemy will not rigidly plan ever last skirmish which can make their plan weak and open to assault.

This point continues along the theme of keeping your enemy off balance and forcing them to make a mistake which you can then exploit.