Fan Sui was a native of the State of Wei during the Warring States period. He originally planned to make a name for himself in Wei, so he became a retainer in the household of Xu Jia, a mid-level official. Once, the King of Wei sent Xu Jia on a diplomatic mission to the State of Qi, and Fan Sui accompanied him. In Qi, Fan Sui impressed the King of Qi with his eloquence and was highly favored. The King of Qi offered him generous gifts and wanted to keep him as a high-ranking guest official, but Fan Sui declined. Unexpectedly, upon returning to Wei, Xu Jia not only failed to praise or promote him but instead falsely accused him before the Prime Minister Wei Qi, claiming that Fan Sui had accepted bribes from the Qi people and betrayed his country. Wei Qi then had Fan Sui thrown into prison and tortured severely. Fan Sui only managed to escape this ordeal by pretending to be dead.
After returning home, Fan Ju changed his name to Zhang Lu to avoid detection and held a funeral for himself to convince Wei Qi that he was dead. Half a year later, when the Qin envoy Wang Ji arrived in Wei, Fan Ju met him through a friend's introduction. The two had a pleasant conversation, and Wang Ji, deeply impressed by Fan Ju's talent, took him back to Qin and found a way to recommend him to King Zhao of Qin.
At that time, the Qin state's court was controlled by King Zhao's mother, Queen Dowager Xuan, and his uncle, the Marquis of Rang. In 270 BC, the Marquis of Rang, seeking to expand his own territory, planned to cross the states of Han and Wei to attack Qi. Fan Ju saw an opportunity and submitted a memorial to King Zhao of Qin, stating that he had important strategies to share and requested a personal audience.
The King of Qin, eager for talent, had Fan Ju brought to the Qin palace in a carriage. After the king repeatedly pleaded, Fan Ju finally said, "The people of Qin only know that the palace has the Queen Dowager and the Marquis of Rang, but they do not know there is a King of Qin." This remark struck a chord with the king, who immediately regarded Fan Ju as someone worthy of trust. Having gained the king's confidence, Fan Ju then spoke the words he had prepared.
To the north, Qin territory includes Ganquan and Gukou, to the south it borders the Jing and Wei Rivers, to the southwest lie Mount Long and the Shu region, and to the east are Mount Xiao and Hangu Pass. With such advantageous terrain, and your vast numbers of chariots and soldiers, shouldn't it be easy for you to overpower the other states? Yet Qin cannot advance eastward even a single step—why is that?
You plan to cross the territories of Han and Wei to attack the powerful state of Qi—this is unwise. If you send too few troops, you won't harm Qi; if you send too many, Qin's own defenses will weaken. Your intention is likely to send fewer troops yourself and have Han and Wei contribute more, but they won't agree. You know full well these two states cannot be trusted, yet you still march through their lands to wage war—isn't that too reckless? In the past, when Qi attacked Chu, they won the battle but gained not even an inch of land. Was it because they didn't want territory? No—it was because their borders couldn't extend that far. Other states, seeing Qi's soldiers exhausted and its internal relations in chaos, joined forces to attack it, crushing Qi completely. Its lands fell into others' hands, and Qi itself became a laughingstock. Why did this happen? Because Qi's campaign against Chu only benefited Han and Wei, which bordered Chu. Isn't that like lending weapons to a robber or giving grain to a thief?
"In that case, it would be better for you to form alliances with distant states while attacking those nearby, so every inch of land you gain becomes your own. Consider how the state of Zhongshan was once so large, yet Zhao swallowed it whole without anyone being able to do anything about it. Now, Han and Wei lie right in the center of the feudal states, occupying a pivotal position. If you wish to achieve hegemony, you must first break through this hub; then Chu and Zhao will feel threatened. Regardless of which of these two states is stronger or weaker, the weaker one will inevitably submit to Qin. Once these two are subdued, Qi will surely panic and also come to submit. With all three states in your fold, won't the remaining Han and Wei be easy to handle?"
The King of Qin said, "I originally wanted to win over the state of Wei, but its stance keeps shifting unpredictably—what should I do?" Fan Ju replied, "First, try to bribe them with wealth; if that fails, offer them territory; if that still doesn't work, then attack them." The King of Qin followed Fan Ju's advice, and two years later, he launched an assault on Xingqiu. After Xingqiu fell, Wei indeed sought to submit to Qin.
After the State of Wei submitted to Qin, Fan Ju further advised: "The territories of Qin and the State of Han are heavily intertwined. With Han sitting right beside Qin, if the situation under heaven ever changes, Han would become the greatest threat. It would be better to bring Han under Qin's control." King Zhao of Qin replied, "I think so too, but what if Han refuses to comply?" Fan Ju said, "You should first attack Xingyang, Han's strategic stronghold for politics, economy, transportation, and military. This would block the route to Chenggao and cut off the northern path to Taihang. The Han troops in Shangdang would also be unable to move south. Han would be split into three disconnected parts. How could they then refuse to obey Qin's orders and submit willingly? Once Han submits, unifying the entire realm will become much easier." King Zhao followed his advice once again.
According to Fan Ju's strategy, the State of Qin would first form alliances with the farthest states, Qi and Chu, attacking from both inside and outside to isolate the central states of Han and Wei, forcing them to submit. Then, Qin would advance north and south, breaking through Zhao and Yan in the north and Chu in the south, integrating their forces, and turning back to eliminate Han and Wei. Finally, with overwhelming superiority, Qin would destroy Qi. In this way, "every inch gained becomes the king's inch; every foot gained becomes the king's foot." This ensured that Qin's victories would not fall into others' hands while consolidating its own strength—this was the strategy of "befriending distant states while attacking nearby ones." The strategy proposed by Fan Ju became the fundamental strategic doctrine for Qin's annexation of the other feudal states. Guided by this principle of "befriending distant states while attacking nearby ones," Qin waged wars across the land for over forty years, ultimately unifying the entire realm and dominating the Central Plains.