Hong Taiji set up a platform in Samjeondo in the upper reach of the Han River. At the top of the platform he accepted King Injo's submission. King Injo kowtowed to Hong Taiji, who allegedly forced Injo to repeat the humiliating ritual many times. A monument in honor of the so-called "excellent virtues of the Manchu Emperor" was erected at Samjeondo, where the ceremony of submission had been conducted. In accordance with the terms of surrender, Joseon sent troops to attack Ka Island at the mouth of the Yalu River.