In 1636, Hong Taiji officially renamed his dynasty the Qing dynasty and invaded Joseon personally. The Qing forces purposely avoided battle with General Im Gyeong Eop, a prominent Joseon army commander who was guarding the Uiju Fortress at the time. A Qing army of 128,000 men marched directly into Hanseong before Injo could escape to Ganghwa Island, driving Injo to Namhan Mountain Fortress instead. They ran out of food and supplies after the Manchu cut all supply lines during the siege. Injo finally surrendered to the Qing dynasty ceremoniously, bowing to the Hong Taiji nine times as Hong Taiji's servant and agreeing to the Treaty of Samjeondo, which required Injo to send his first son and second son to China as captives. Joseon then became a tributary state to the Qing dynasty, and the Qing went on to conquer the Central Plain in 1644. Though they lost the wars, their performance left a strong impression on the Manchus. The first emperor of the newly declared Qing dynasty later wrote: "The Koreans are incapable on horseback but do not transgress the principles of the military arts. They excel at infantry fighting."Andrade, Tonio (2016). "The Gunpowder Age: China, Military Innovation, and the Rise of the West in World History." Princeton University Press. Page 187.
