Battle of Shanhai Pass - Prelude - Rise of The Manchus

Rise of The Manchus

As the Ming dynasty faltered and the threat from northern enemies grew, Ming emperors saw the strategic value of Shanhai Pass and frequently garrisoned troops there, armies which sometimes reached up to 40,000 men. Under Emperor Hung Taiji (r. 1626–1643), the Qing was becoming more aggressive against the Ming. After an intermittent siege that lasted over ten years, Qing armies led by Jirgalang captured Songshan and Jinzhou in early 1642. The garrison of Ming general Wu Sangui in Ningyuan became the only major army standing between the Qing forces and the Ming capital in Beijing. In the summer of 1642, a Qing army managed to cross the Great Wall and ravaged northern China for seven months before withdrawing in May 1643 with prisoners and booty, without having fought any large Ming army.

In September 1643 Hung Taiji suddenly died without having named an heir. To avert a conflict between two strong contenders for succession – namely Hong Taiji's eldest son Hooge and Hung Taiji's agnate brother Dorgon, a proven military leader – a committee of Manchu princes chose to pass the throne to Hong Taiji's five-year-old son Fulin and appointed Dorgon and Jirgalang as co-regents. Because Jirgalang had no political ambition, Dorgon became the prime ruler of the Qing government.