Listen to this articleɡānchénɡ 干城
Shield and Fortress / Dukes and Princes
本指盾与城，后用来比喻诸侯，以及国家政权、理论主张等的捍卫者。“干”即盾，是古代的一种防御性武器；“城”即城墙或城郭，是具有防御功能的建筑设施。用“干城”比喻诸侯，与“崇城”（比喻天子）相对。称天子为“崇城”，表明天子地位之崇高、优越；称诸侯为“干城”，表示诸侯的职责是拱卫天子，必须服从天子号令。后泛指忠实得力的保卫者——不仅指地位低的人保卫地位高的人，有时也指地位高的人保卫地位低的人。
The term originally referred to shield and fortress, but was later used to mean dukes and princes, and then defenders of a regime, theory or proposition. Gan (干) means shield, a defensive weapon in old days, while cheng (城) means inner and outer city walls or a fortress, a structure for defensive purposes. Dukes and princes were likened to gancheng (干城), in contrast with chongcheng (崇城), which means supreme city, referring to the Son of Heaven and indicating his supreme position. It is meant that dukes and princes, likened to shield and fortress, had the responsibilities to defend the Son of Heaven. Hence, dukes and princes must obey orders from the Son of Heaven. As it has evolved over time, the term generally referred to loyal and efficient defenders. Interestingly, it came to mean that not only people of lower ranks defend their superiors, but also people of high positions defend their subordinates.
引例 Citations：
◎天子曰“崇城”，言崇高也；诸侯曰“干城”，言不敢自专，御于天子也。（《初学记》卷二十四引《白虎通》）
（天子称“崇城”，意思是说天子居于崇高、尊贵的地位；诸侯称“干城”，意思是说诸侯不敢擅自行动，必须听命于天子。）
The Son of Heaven is referred to as chongcheng, indicating his supreme and noble status, while dukes and princes are referred to as gancheng, meaning that they must not act on their own but pledge their obedience to the Son of Heaven. (Debates of the White Tiger Hall)
◎赳赳武夫，公侯干城。（《诗经·周南·兔罝》）
（雄赳赳的武士，是诸侯的保卫者。）
The valiant warriors are defenders of dukes and princes. (The Book of Songs)
◎天下有道，则公侯能为民干城。（《左传·成公十二年》）
（如果国家政治清明，那么诸侯们就能成为百姓的保卫者。）
With good governance, dukes and princes become defenders and protectors of their people. (Zuo’s Commentary on The Spring and Autumn Annals)
