Peace proposals unaccompanied by a sworn covenant indicate a plot.
Attack like the Fire and be still as the Mountain
So the principles of warfare are: Do not depend on the enemy not coming, but depend on our readiness against him. Do not depend on the enemy not attacking, but depend on our position that cannot be attacked.
If you know neither the enemy nor yourself, you will succumb in every battle
If a battle can not be won do not fight it.
It is essential to seek out enemy agents who have come to conduct espionage against you and to bribe them to serve you. Give them instructions and care for them. Thus doubled agents are recruited and used.