If a battle can not be won do not fight it.
In desperate position, you must fight.
The best general is the one who never fights.
If you fight with all your might, there is a chance of life; where as death is certain if you cling to your corner
So in war, the way is to avoid what is strong, and strike at what is weak.
War is a matter of vital importance to the state; the province of life or death; the road to survival or ruin. It is mandatory that it be thoroughly studied.