城下之盟 a treaty concluded with the enemy who have reached the city wall; sign a dishonourable peace as the defeated; terms accepted under duress; terms for surrender; treaty [contract] made [signed] under coercion; treaty signed below the city wall to avert destruction
海上之盟 alliance between sung and kin over the sea (公元1120年宋、金联合攻辽的盟约)
秦晋之盟 marriage alliance between the states of qin and jin