After Duke Mu of Qin , Zi Yao came to the throne on his behalf, Duke Kang of Qin .
Duke Xiang of Jin State , the heir of Duke Wen of Jin Chong'er also passed away. The powerful minister Zhao Dun planned to make Xianggong's younger brother Yong the king. Yong was in the state of Qin as a hostage at that time.
Zhao Dun sent a follow-up party to pick up Yong. Unexpectedly, something went wrong. Jin Xianggong 's wife Mu Ying firmly disagreed with establishing Yong as the monarch. Zhao Dun was under pressure and had no choice but to appoint Prince Yigao as the throne instead. Qin Guo, Suihui and others did not receive this information in time. Duke Kang of Qin also sent troops to escort Yong back to Jin. As a result, the Qin army did not know that Yong was still dreaming, and the people accompanying him were still waiting to return home to receive the reward.
On a dark night, the Jin army suddenly appeared. Zhao Dun, who was in charge, met the others and said to himself, "Don't fight your own people." Unexpectedly, the Jin army killed them fiercely, and the Qin army was defeated by Linghu, who then went to Qin. Duke Kang of Qin used him very much.
Qin Kanggong couldn't swallow this breath. The next year, he sent troops to attack Jin with his accountant and occupied Wucheng, which was regarded as revenge for the Battle of Jinhu.
Jin was unwilling to give up. Two years later, he attacked Qin and occupied Shaoliang.
In this way, the friction between the two countries continued, and the people of Jin suspected that Sui Hui was causing sabotage in the Qin State, so they sent Wei Juyu to trick Sui Hui into returning to Jin with a trick of surrender, and he joined the cabinet and became Zhao Dun's right-hand man.
Qin Kanggong also liked to have fun, so he spent a lot of time and effort to build a luxurious
observation deck, which took three years to complete. Public dissatisfaction came and the court was unstable. Chu State saw an opportunity and sent troops to attack Qi State .
Qin Minister Ren Wang went to Shu Qin Kanggong and said that famine will attract enemy soldiers; disease and plague will attract enemy soldiers; heavy labor will attract enemy soldiers; and political chaos will also attract enemy soldiers. The Chu State's attack on Qi was a strategy of attacking from the east and attacking from the west, hoping to take advantage of the chaos to sneak attack on our Qin State.
Duke Kang of Qin was not confused yet and quickly sent troops to strengthen the eastern border. The Chu army's squadron returned home.
During Qin Kanggong's reign, many confrontations with the Jin State caused the decline of Xirong's dominance.
Duke Kang of Qin died in the twelfth year of his reign, and his son Prince Dao came to the throne.