In the spring of the fourth year of Duke Lu Yin (BC719), Duke Zheng Zhuang was ready to go to the court to meet King Huan of Zhou with a rich tribute, but he did not take a step out after all.

It turned out that Song Mugong died last fall, but this incident will not affect Zheng Zhuanggong's itinerary; Soon Feng, the crown prince of the Song Kingdom, went into exile in the Zheng Kingdom, which would not affect his itinerary; But what is fatal is that Gongzi Feng is followed by chasing soldiers all over the mountains, not one country, but the entire army of four countries, and the coalition forces put on a posture of not killing Gongzi Feng and vowing not to give up.

This was too appalling, and Zheng Zhuang Gong had no choice but to cancel the trip and stay in the country to fight the invading enemy.

The turmoil in the Song Kingdom stemmed from the absurd decision of Song Mugong on his deathbed. When he was critically ill, he called the great Sima Confucius to the couch and said: "The ancestor Xuangong (the elder brother of Song Mugong) gave up with Yi (the eldest son of Xuangong) and became a widow, and the widow did not dare to forget the great virtue of the ancestor.

"During the nine years of the widow's reign, the blessings of the doctors were able to pass smoothly. If the widow accepts the throne from the ancestor and passes it on to his son, then when the widow returns to heaven and the ancestor asks about Heyi, how should the widow answer? Therefore, please establish and raze as kings, and ask the doctors to serve wholeheartedly, so there will be no regrets for such a widow. ”

Kong Fatherjia was very surprised, and he replied: "But you have already made Gongzi Feng the crown prince, and he is ready to take over the throne, and the ministers are willing to serve him as king."

"Now that he suddenly deposes the crown prince's status as the prince and pushes a prince with a mediocre status to a high position, Feng will definitely not be reconciled and will inevitably snatch the throne. And if he Yi keeps the throne, he will definitely get rid of Feng and then quickly. In this way, the royal family will definitely be in turmoil, the children of the country will kill each other, the country will be weakened, and foreign enemies will take the opportunity to invade! So please take back your order! ”

Song Mugong said: "No! The ancestor thought that the widow was virtuous, so he ordered me to preside over the society. If the widow abandons and establishes Feng, it is the election of the ancestor to be abandoned, where is there still a good name to speak of? Will the widow live up to the expectations of his ancestors because of my son? Let Feng go to Zheng Guo and never come back! So that the brothers will not kill each other, and you will not force the widow to abolish the ancestors! ”

Song Mugong died in August, and Gongzi and Yi ascended the throne as Song Mugong. After the funeral, Gongzi Feng went to Zheng Guo.

Since Gongzi Feng was exiled to Zheng State in full accordance with his father's will, and Song and Zheng had reached an agreement on this matter in advance, Zheng Guo's containment of Gongzi Feng did not affect the diplomatic relations between the two countries. But soon, due to the bad guys, Zheng and Song became hostile countries, and the hostile state did not change until the Spring and Autumn Period.