Li Jing was a strategist from the late Sui Dynasty to the early Tang Dynasty. Li Jing fought for decades all his life and made great contributions to the establishment and development of the Tang Dynasty. His experience in running the army further enriched China's ancient military thought and art of war theory. He wrote many military books, such as The Mirror of Six Armies and The Art of War in Gong Wei, many of which have been lost.

Li Jing's military thought is 1. Emphasis on preparing for emergencies: Li Jing believes that only by preparing well at ordinary times can we be in an invincible position. He said: "If soldiers are not prepared, they should not die. If they lose the chance, they are useless. If they lose their chance, they will be defeated. "

2. Focus on seeking instead of fighting: Li Jing pointed out: "The husband's decision is to use his talents in Kocha, to judge the strength of the enemy, to judge the situation of the land, to observe the interests of the time, to win first and then fight, and to remain unbeaten, which is also the way to win." If there is no plan to fight for the leader, it is tantamount to "rushing to the soup and fire all your life, driving away cattle and sheep, spitting wolf and spitting tiger."

3. Emphasize the appropriateness of attack and defense, depending on the situation: For the two basic types of operations, Li Jing not only reveals the dialectical relationship between attack and defense with the conclusion that "attack is the opportunity to defend, defense is the strategy to attack, and both win", but also further expounds the truth that attack and defense are appropriate, depending on the situation, and expounds the strategic thinking of "lasting defense". He said, "Although you love soldiers, you can't take advantage of them." But when "the enemy will be resourceful, the soldiers will be reconciled, and the order will be banned, the soldiers will benefit from four strengths, the gas will be fierce, and the strength will be full." "Then when you store up, the surplus will be exhausted, and you will avoid the front for a long time."