1597年，明、日议和破裂，兵戈再起。朝鲜遣使入京乞援，明朝再度发兵朝鲜。山东右参政杨镐被擢升为都察院右佥都御史，经理朝鲜军务。蔚山之战后，军中有人检举杨镐组织撤退不利，叙功不公。丁应泰在调查后决定撰写奏文弹劾杨镐。朝鲜国王李昖派遣陈奏使入京为杨镐说情。丁应泰得知朝鲜为杨镐求情，遂将矛盾扩大化。他再入朝鲜时偶得一本《海东诸国纪》，书中内容记录了朝鲜同日本来往等事，丁应泰据此弹劾李昖引狼入室，意在辽东。朝鲜君臣一时震骇不已，李昖闭门待勘，并遣陈奏使入京辨诬。此次辨诬，朝鲜使臣获得咨文证其无辜，朝鲜为忠诚恭顺之东藩的地位得到认可。李昖薨逝，其子李珲继位，明朝使臣渡江赐祭、赐谥，朝鲜君臣鉴镜于丁应泰弹劾朝鲜僭越，称祖称宗，就李昖的神主该如何设立展开大讨论。数年后，朝鲜使臣赴华时偶得汉文书籍，内有类似丁应泰弹劾李昖时之说辞，李珲针对该部分内容派遣陈奏使入京辨诬，此行获得敕文，昭雪天下。

通过研究丁应泰弹劾杨镐、朝鲜的经过以及朝鲜做出的反应，可以知道中朝缔结宗藩关系时缺乏政治互信。这场纷争为理解宗藩关系的复杂性和不平等性提供了一个切口。

In 1597, the peace negotiations between the Ming Dynasty and Japan failed, resulting in the resumption of war. An offensive was launched by Japanese troops on the Korean Peninsula. In light of the strategic relationship between the Joseon Dynasty and the Ming Dynasty, the latter sent troops to Joseon once again. As a result, Yang Hao（杨镐）, a government official in the Ming Dynasty, was promoted to manage the military affairs of Joseon. After the Battle of Ulsan（蔚山）, some people in the army reported to Ding Yingtai（丁应泰）, a supervisor from the Ming Dynasty, that Yang Hao was grossly negligent in his duties. After the investigation, Ding Yingtai decided to prosecute Yang Hao for 28 crimes. The King of Joseon, Yi Yeon（李昖）, sent envoys to Beijing to intercede for Yang Hao. When Ding Yingtai learned that Joseon was interceding for Yang Hao, he widened the conflict. On his re-entry into Joseon, Ding Yingtai obtained a copy of the Haidong Jilve（《海东纪略》）, which recorded Joseon's interactions with Japan. Based on this, Ding Yingtai impeached Yi for collaborating with Japan to invade Liaodong. Yi and Joseon officials were shocked. Following the allegations, Yi placed himself on suspension while awaiting inspection and sent envoys to Beijing to clear his name. The Ming Dynasty heard Joseon's side of the story and acknowledged that the accusations were false. Joseon's loyal and obedient vassal status was reinstated. After Yi Yeon's passing, his son Yi Hon took over the throne. The Ming Dynasty sent envoys to offer condolences and confer a posthumous title on Yi Yeon. The Joseon government recalled the false accusations made against them by Ding Yingtai, who claimed they had overstepped their bounds and used temple titles. Years later, Joseon's envoys acquired Chinese books containing similar false claims to those made against Yi Yeon, prompting Yi Hon to send envoys to Beijing to defend themselves. This time, the envoys returned with a Royal Decree that cleared Joseon's name and proved their innocence to the world.

Through examining the impeachment of Yang Hao and Joseon by Ding Yingtai, as well as the subsequent response by Joseon, it becomes apparent that the Ming Dynasty and Joseon entered into a suzerain-vassal relationship that lacked political trust. This dispute provides valuable insight into the intricate and unequal nature of such relations.