Under repeated demand from Ming, Gwanghaegun commanded Gang Hong-rip to help Ming forces with ten thousand soldiers against the Manchus in 1619. However, Ming armies were crushed in the Battle of Sarhū. The Korean army under command of Liu Ting lost two-thirds of his troops at Fuca and surrendered to Nurhaci. Official Korean records say that Gwanghaegun had ordered a betrayal to Nurhaci, but it is considered defamation by the Westerners faction, who deposed the king. In 1620 almost all Korean captives were released but he was still kept.
Frustrated with unsatisfactory reward for the coup which Gwanghaegun was deposed by, Yi Gwal (李适) rebelled against King Injo in 1624. He temporarily occupied Hanseong (modern-day Seoul), but was eventually crushed. Han Myeongnyeong (韓明璉), an accomplice of Yi Gwal, was also killed, but his son Han Yun (韓潤) fled to the Manchus.
Gang Hong-rip fell for Han Yun's trick and wrongly believed that his family was all killed by the government. To get his revenge on Korea, he urged the Manchus to defeat the dynasty. In 1627 he guided the Manchu army led by Amin to Hanseong and as a Manchu delegate he negotiated for a truce with Korea. Then he waked to the fact about his family and suffered a heartbreak. He was branded as a traitor and deprived his official rank. He was rehabilitated after his death.