戰國末期演變成七雄爭霸，秦國經過商鞅變法後，國力愈來愈強，秦昭王開始計畫吞併其他六國，想要獨霸中原。
公元前270年，秦昭王下令出兵攻打齊國，宰相范睢便向秦昭王獻上「遠交近攻」的策略，阻止攻打齊國。
范睢說：「齊國是六國中最強大的，離秦國又很遠，要是先攻打齊國，我國軍隊就要經過韓、魏兩國領土。軍隊少，很難獲勝；軍隊多，就算打贏了也沒辦法占有齊國的土地。不如我們先攻打鄰近的韓、魏兩國，再逐步推向齊國。」又為了防止齊國與韓、魏結盟，秦昭王就派使者主動與齊國結盟。
接下來的四十多年，秦始皇便延續「遠交近攻」的政策，遠交齊楚，首先攻下韓、魏，後來又從兩側出兵，攻破趙、燕，統一北方；接著攻下楚國，平定南方；最後才把齊國也收拾了，征戰多年，終於實現統一中國的願望。
三十六計之第二十三計：遠交近攻
當地形受到限制時，可以先從近的目標下手，再逐步向遠的地方擴張領域。
Near the end of the Warring States Period, the political situation had developed into a struggle for supremacy among the seven strongest countries. After the reforms instituted by Shang Yang, Cin grew stronger by the day. So king Cin Jhao started plans to conquer the remaining six countries to create the first unified empire in China.
In 270 BC, king Cin Jhao wanted to conquer Ci, but his prime minister Fan Suei advised against this. Instead, he presented king Cin Jhao with a scheme to befriend a distance state and attack the ones nearby.
Fan Suei said, "Among the six countries, Ci is the strongest and the farthest away from Cin . If we attack Ci now, our troops must first go through the territories of Han and Wei. With too few troops, it is difficult to conquer Ci. But with enough troops, it would still be impossible to occupy Ci even if we won. We would be in a no-win situation. Therefore, why not attack the neighboring Han and Wei first and then advance towards Ci step by step?" In addition, in order to prevent Ci from allying with Han and Wei, king Cin Jhao took the initiative to form an alliance with Ci.
In the forty years that followed, Cin followed the same policy: Form alliances with Ci and Chu, while taking Han and Wei first. Later, Cin conquered Jhao and Yan to unify the north. Afterwards he conquered Chu in the south. Finally, Cin was able to conquer Ci. King Cin Jhao's dream of unifying China was thus finalized. This was how king Cin Jhao became Cin Shih Huag, the first emperor of China.
Strategy 23: Be friend a Distant State and Conquer the Ones Nearby
When constrained by terrain, you should start with the closest objective and gradually extend your forces further.
