"The Northern Expedition of the Early Ming Dynasty broke through Mongolia": Zhou Yan was a member of the Ming Dynasty's Northern Expedition, and accompanied Lan Yu in the expedition to Mobei. After the army penetrated deep into the Mongolian grassland, they were short of food and grass. They also encountered the Mongolian army's "false surrender plan" and the camp was attacked at night. Zhou Yan led fifty soldiers to guard the grain road and used Zhuge's crossbows to repel the Mongolian cavalry, giving the army a chance to reorganize its formation.
