Despite the surrender of its throne, Paekche died neither quietly nor willingly. A small defiant group led by King Uija's nephew, Poksin, and a Buddhist monk named Toch'im devised plans to restore the Paekche throne. They recruited an armed force from Churyu-song near modern Hansan and led their small band of rebels in numerous attacks against Silla and Tang troops in the Kum River basin. They even brought Paekche's Prince P'ung back from Japan and placed him on the "restored throne." Paekche rebels continually harassed Tang military garrisons in the area, successfully laid siege to the cities of Sabi and Ungjin, and recaptured over two hundred strongholds in furious battles throughout the region. They and occasionally defeated the Tang and Silla armies sent to suppress them.
The Paekche restoration movement had strong popular support, but it lacked cohesive leadership at the top and internal dissension soon tore it apart. Poksin cruelly murdered Toch'im and Prince P'ung ordered Poksin's execution. Desperate for help, Prince P'ung sent envoys to both Koguryo and Japan to get troops to fight the Tang-Silla invaders. One of his brothers, Prince Yung, who had earlier been taken to the Tang capital at Changan as a prisoner, returned to Paekche as a guide for a fleet of Chinese warships and supply ships.
The Chinese sailed south from the Ungjin River to link up with Silla forces camped near the mouth of the Kum River. As they arrived, the Chinese unexpectedly encountered a vast number of Japanese ships anchored near the river mouth. In the surprise naval battle that followed, the Tang-Silla force won a great victory, claiming to have sunk or destroyed some 400 Japanese ships. The disastrous loss of Japanese reinforcements broke the Paekche restoration movement. The combined armies of Silla and China took quick advantage of Paekche's internal conflict and seized the rebel stronghold at Hansan. With its leadership gone and no possibility of outside help, remnants of rebel units surrendered one after another. The three-year struggle to restore Paekche ended with the capture of the last rebel fortress at Imjon-song near modern Taehung.