In 284 BC, the State of Yan attacked the State of Qi with forces commanded by Yue Yi, and managed to corner Qi within the city of Ju, the state's final stronghold. Although Qi lost a significant portion of territory, they were able to successfully counterattack against Yan under the leadership of Tian Dan and retake its lost territory within five years.
The idiom 毋忘在莒 (do not forget what happened in Ju) has two allusions with differing meanings, one of which refers to Qi's successful counterattack against Yan from the city of Ju, and is used to represent a retaking of one's homeland. The idiom was used by the Chiang Kai-shek-led Republic of China government after relocating to Taiwan in its effort to retake mainland China.
