管城 / Guancheng (Warring States)
管城 / Guancheng enters the wiki through 《资治通鉴·秦纪》103-1｜司马迁看中的信陵君算是小人吗？ as the city 信陵君 wants to take after defeating 蒙敖. The episode treats Guancheng as part of the remaining Qin pressure on 魏国 after the immediate battlefield victory.
Its importance is geographical. The source says Qin already controls 荥泽 southeast of Guancheng and 荥阳 to the northwest of Xingze, meaning Qin may threaten 大梁 by controlling water routes. Guancheng therefore turns a successful anti-Qin coalition victory into a follow-on city-control problem.
Guancheng is also the site behind the source’s ethical conflict. 苏高 refuses to attack because his son is defending the city for 秦国, while 安陵君 refuses to surrender Su Gao to Xinlingjun. The city therefore links military necessity to 国存亡与父子君臣义冲突.