居庸関
In July, the imperial staff surrounded the Yan residence, and Zhu Di responded by executing the imperial staff and then storming the gates of Beiping. By nightfall, Zhu Di was in control of the city and had officially rebelled against the imperial court. For the next several days, the Yan forces captured Tongzhou, Jizhou, Dunhua and Miyun. By the end of July, Juyong Pass, Huailai and Yongping all fell to the Yan forces and the entire Beiping area was effectively under Yan control.