The Art of War · Chapter
IX: The Army on the March explained
Sun Tzǔ discusses the principles of encamping an army and observing signs of the enemy.
What happens
Sun Tzǔ discusses the principles of encamping an army and observing signs of the enemy. He covers tactics for different terrains: mountains, rivers, salt-marshes, and flat country. He emphasizes the importance of choosing high, sunny, and hard ground for camps to prevent disease and ensure victory. The chapter also details how to interpret enemy movements, sounds, dust, and behavior to anticipate their intentions, and stresses the need for humane treatment combined with iron discipline to maintain an effective army.
Themes in this chapter
Strategic Use of Terrain and Environment
The entire chapter focuses on how to encamp and maneuver in mountains, rivers, marshes, and flat land, and how to use natural features to one's advantage.
Psychology and Morale
Detailed observations of enemy behavior (e.g., humble words, violent language, whispering, rewards, punishments) reveal psychological states and intentions.
Leadership and Discipline
The chapter concludes with the necessity of treating soldiers with humanity while enforcing iron discipline to ensure obedience and victory.
Characters to notice
Key passages
“Pass quickly over mountains, and keep in the neighborhood of valleys.”
When moving through mountainous terrain, move swiftly and stay near valleys for easier travel and supply.
Sun Tzǔ advises rapid movement through mountains while using valleys as natural corridors.
“When an invading force crosses a river in its onward march, do not advance to meet it in midstream. It will be best to let half the army get across, and then deliver your attack.”
If the enemy is crossing a river, do not attack while they are in the water; instead, strike when part of their force has crossed and is disorganized.
This classic tactic exploits the enemy's vulnerability during river crossings.
“All armies prefer high ground to low, and sunny places to dark. If you are careful of your men, and camp on hard ground, the army will be free from disease of every kind, and this will spell victory.”
Armies should always camp on high, sunny, and firm ground to keep soldiers healthy, which leads to victory.
Sun Tzǔ emphasizes the importance of camp placement for troop well-being and morale.
“When the enemy is close at hand and remains quiet, he is relying on the natural strength of his position.”
If the enemy is near but stays still, they are confident in their defensive terrain.
Observation of enemy stillness indicates reliance on terrain advantages.
“If soldiers are punished before they have grown attached to you, they will not prove submissive; and, unless submissive, then will be practically useless. If, when the soldiers have become attached to you, punishments are not enforced, they will still be useless.”
Punishing soldiers before they are loyal makes them rebellious; but after loyalty is earned, discipline must be enforced or they become ineffective.
Sun Tzǔ balances humane treatment with strict discipline for effective command.