The main topic of chapter 12 is the use of fire in attack. For example,
If fire is set inside, respond immediately from the outside.
If fire is set and his military is still, do not attack.
Rush to where the fire is calamitous.
The chapter also warns against the general's or ruler's anger as a motive for attack:
Wrath can return to joy.
Rancor can return to delight.
An extinguished state cannot return to existence.
The dead cannot return to life.