During the Wanli Dynasty, the Ming Dynasty's border security was quite effective, which depended on the two famous generals of the border pass: Qi Jiguang in the southeast and Li Chengliang in the northeast. At that time, Li Chengliang's prestige was far superior to Qi Jiguang's. In the era when the Ming generals were greedy and cowardly, and the border was prepared and abandoned, Li Chengliang crisscrossed the northern border plugs, guarded liaodong for nearly thirty years, repeatedly broke through strong and powerful, suppressed the nomadic tribes in the north on all sides, and expanded the territory for nearly a thousand miles. Liaodong became a solid barrier, and trade markets were opened in Kaiyuan, Qinghe, Fushun and other places to establish friendly relations with local tribes.
During his time in liaodong, he had a good personal relationship with Nurhaci, who grew in strength with the inclusion of Li Chengliang's wings, and the Ming government even granted Nurhaci the official position of "Dragon and Tiger General". During Li Chengliang's second defense of Liaodong, his various practices were constantly impeached by Ming officials, but the Wanli Emperor did not take too much harsh rebuke of Li Chengliang in view of Li Chengliang's great use value in Liaodong, and Nurhaci only established the Later Jin regime in Hetuala a few months after Li Chengliang's death.
Looking at Wu Sangui again, during the reign of Qing Shun, Wu Sangui, the former chief soldier of Mingshan Customs, was named "King of Pingxi" by the Manchu Qing Dynasty in Yunnan, and in the early days of Wu Sangui's domain in Yunnan, the power of the Yongli small court in southern Yunnan was still very large, and Wu Sangui's attitude towards the Yongli small court was "chasing and fighting fiercely" until June 1, 1662, when Wu Sangui killed all the Yongli Emperors and his family who had been sent back from Burma.
After that, Wu Sangui lost its use value for the Manchu Qing, and soon after the Kangxi Emperor of the Qing Dynasty began to withdraw his domain, forcing Wu Sangui to rebel against the Qing in 1673, and 8 years later, the Qing army attacked Kunming, and Wu Sangui's grandson Wu Shifan committed suicide with his family.
Li Chengliang could not destroy all the tribes in the frontier, so he integrated the strength of the various tribes, let them have contradictions between them, attacked each other and hurt each other, so as to achieve a balance, so that they could not unite against Daming, and all tribes had to take Daming as a backer, so as to make the frontier safe, which was his cleverness. Chiang Kai-shek did this when he controlled his subordinates, artificially creating contradictions among the various generals in order to achieve the goal of controlling them. This practice can be used on the enemy to divide and disintegrate the enemy, and to use it on one's own hands is to dig one's own grave, because one's own men are divided, not united, and all consider their own interests, then one side will have difficulties and ignore them, and eventually lead to failure.
On The side of Wu Sangui, Yongli retreated into Burma after defeat, and Li Dingguo guerrilla attacked the border, which did not make Wu Sangui consider the capital of "raising Kou and self-respect", and if the Yongli regime existed for a long time, it might be possible.
Secondly, the Qing court did not trust the Han people and always had a suspicious mentality towards Wu Sangui, who could only gain the trust and power of the Manchu Qing if he desperately served the Manchu Qing and destroyed the Yongli.
Third, if Wu Sangui had already had different ambitions, he would have found ways to raise Kou and respect himself, which also reflected that Wu Sangui did not plan for a long time to oppose the Qing, and was forced to rebel by the Manchu Qing.
Later, Wu Sangui rebelled against the Qing Dynasty, and the reason why some of the former dynasty elders and scholars did not support him was not only because of his moral integrity, but also because he could not do it, and they were not sure whether Wu Sangui could succeed. Wu Sangui is an officer type rather than a commander type, he is outstanding in tactics, but strategically it is a short board, Wu Sangui basically did not do what the commander did before the anti-Qing, naturally there will be no commander's thinking and talent.