During the Warring States period, the Yan general Yue Yi allied with Qin, Zhao, Wei, and Han to invade Qi. Qi suffered a crushing defeat, leaving only the cities of Ju (modern Ju County, Shandong) and Jimo (southeast of modern Pingdu, Shandong) standing. King Min of Qi was forced to flee to Ju.
Tian Dan, a distant relative of the Qi royal family, had long been overlooked for his talents and fled with his family to Jimo. When the city's commander fell in battle, the people turned to Tian Dan, urging him to lead the defense.
Tian Dan, a master of strategy beloved by his people, had held out in Jimo for three years against the siege of the powerful general Yue Yi. Knowing he could not defeat Yue Yi by force alone, Tian Dan devised a plan: he sent spies to the Yan capital to spread rumors that Yue Yi harbored ambitions for the throne. The whispers reached King Hui of Yan, who grew suspicious and replaced Yue Yi with the general Qi Jie.
Qi Jie, lacking both talent and kindness, was harsh and cruel to his men, causing deep dissatisfaction among the Yan army's officers and soldiers. Gradually, their morale crumbled and their fighting spirit waned.
Tian Dan saw his moment had arrived. He sent agents to spread rumors that the state of Qi had divine protection, while secretly hiding his elite troops and putting the elderly and women on the walls to guard the city. He also dispatched envoys carrying large sums of gold to Qi Jie, the Yan commander, offering surrender and begging for their lives when the Yan army attacked. This lulled the Yan forces into lowering their guard.
Tian Dan gathered over a thousand oxen, draping each in cloth painted with bizarre patterns, tying sharp blades to their horns, and fastening oil-soaked reeds to their tails.
In the dead of night, the Qi army drove oxen through a tunnel they had secretly dug under the city wall, lit the reeds tied to their tails, and forced the beasts to charge straight into the Yan camp.
Caught off guard by this sudden monstrous assault, the Yan soldiers screamed and leaped in terror, scattering in every direction. Some were trampled to death, others were gored by the sharp knives tied to the oxen's horns, and many were burned alive. Even those who managed to escape the blazing oxen formation were cut down by the five thousand elite troops waiting behind.
The Yan army suffered a crushing defeat, and their general Qi Jie was captured and executed
Later, the idiom "winning by surprise" came to be used to describe using unexpected tactics and strategies in battle to defeat the enemy.
Source: *Records of the Grand Historian*, "Biography of Tian Dan"
Meaning of the Idiom: Later, the Chinese idiom "出奇制胜" came to describe using unexpected tactics and strategies in battle to defeat the enemy.