There are five ways to use fire against an opposing army: by burning its camp, setting fire to its stores, burning its supply line, igniting its arsenal, and by raining fire down on it.

It is best to use fire when a wind comes up; certain times of year are usefully windy; daytime breezes often falter at sunset, while nighttime winds can fail at dawn. Once a fire is set and enemy troops panic, they may be picked off as they escape the flames. Always attack from behind the advancing flames. Water also can be diverted toward an enemy, but it cannot destroy provisions as fire does.

Clever use of fire is an example of the innovative thinking that distinguishes a victorious leader and a successful ruler. 

Knowing the enemy’s plans is vital to success in war. For this, five types of spies are available: local, or native spies paid to inform; inward, or members of the enemy government turned to the invader’s use; converted, or captured spies treated well and turned into counterspies; doomed spies fed false information and betrayed, who, under interrogation by the enemy, give inaccurate data; and surviving spies, who go undercover, risk exposure, and return with vital intelligence.