Introduction to the Tenth Chapter: The Tenth "Terrain Chapter" discusses how to use terrain in military operations, focusing on the benefits of fighting deep into the enemy's country. Sun Wu analyzed the characteristics of nine types of battlefields and the psychological state of soldiers in these areas, and accordingly proposed different measures for using troops in these areas. He believed that going deep into the enemy's country would be equivalent to putting soldiers in danger and into death, and they would be forced to do so. They have fought desperately to exert greater combat effectiveness. Moreover, when they go deep into the enemy's country, they can replenish their military rations on the spot. They can also not escape because they are too far away from home. They can obey the command, fight with one heart and one mind, and win the war.