Joseon helped Ming China with 10,000 soldiers when Ming China attacked Manchurian Later Jin under Nurhaci in 1619, but Korean General Gang Hong-rip surrendered to Nurhaci. Gang insisted that Korea did not hold anything against the Manchus and that he sent reinforcements only to repay an obligation to Ming. The first Manchu expedition was triggered by Yi Gwal's rebellion against King Injo in 1624. The revolt was soon crushed but remnants fled to Manchuria. They recommended Hong Taiji to invade Korea.