Hanzi

During the Spring and Autumn period, the vassal state of Zheng was powerful. Duke Zhuang of Zheng served as a high minister (Qingshi) of the Zhou dynasty, wielding great power in the court. Relying on his influence and status, he held the Zhou emperor in contempt.

King Ping of Zhou, who was the emperor at the time, was a weak and incompetent ruler. He had to rely on Duke Zhuang of Zheng to manage the Zhou court's affairs, yet he deeply trusted a certain Duke Jifu and wanted him to replace Duke Zhuang of Zheng in handling the court. When Duke Zhuang of Zheng learned of this, he became extremely displeased with King Ping of Zhou. King Ping, greatly alarmed, quickly explained to Duke Zhuang that he had no intention of having Jifu replace him. To gain Duke Zhuang's trust, King Ping and Duke Zhuang exchanged hostages: Crown Prince Hu of Zhou went to Zheng as a hostage, and Prince Hu of Zheng came to the Zhou court as a hostage.

In 720 BC, King Ping of Zhou died, and his grandson Ji Lin succeeded him, known as King Huan of Zhou. King Huan also wanted Jifu to replace Duke Zhuang of Zheng as the high minister in charge of the court's affairs. Upon learning this, Duke Zhuang of Zheng was enraged. He dispatched his high official Zhai Zu (祭足) to lead troops to harvest wheat in Wen, a territory of the Zhou dynasty, and transport all of it to Zheng. In autumn, Zhai Zu again led troops to Cheng Zhou, another Zhou territory, harvested all the grains there, and brought them back to Zheng.

From then on, the relationship between the two states deteriorated further, and a deep animosity formed between them. Words not spoken from the heart, even exchanging hostages is useless. This was the incisive comment made by the historians of the time regarding this matter.