Wubei Zhi, Volume 129

Supreme Commander Xing Jie referred to here by his surname "Xing" waited for the unified forces to launch a grand offensive. The Japanese original: "Wa" (倭) forces were positioned along the river, holding their ground so firmly that their formation resembled a long, coiled snake. Zhu Guoqi referred to by his style name "Guoqi" observed: "Looking at their tactical disposition, Mangjin original: "Wangyang" (望洋); a strategic point near the Nam River is the 'head' of the snake. If the head is crushed, the entire defense will immediately collapse. However, the Nam River original: "Jinjiang" (晉江) cannot be crossed as if by flight; we must take it through a clever ruse."

A scouting patrol captured a woman coming from the Japanese camp. From within her robes, she produced a letter which read: "This woman was about to be taken to a foreign land referring to being taken as a captive to Japan. I took pity on her and ransomed her. I ask that the Heavenly Soldiers The Ming Imperial Army do not harm her." The end of the letter contained a riddle: "He who knows my surname is the descendant of the Lord Commander Refers to the famous Tang dynasty General Guo Ziyi and the father who buried his son Refers to Guo Ju, a figure of legendary filial piety. He who asks my name: it has the 'mouth' of 'perhaps' The character huo (或) but lacks the 'hand' of 'pressing' The character an (按) without the hand radical shou (扌) is an (安)."

Zhu Guoqi and the strategist Zhuge Xiu solved the puzzle, declaring: "This is Guo Guo'an." They reported this to the staff officer Shi Shiyong. Shi Shiyong reacted with excitement, saying: "Guo Guo'an is a Chinese man! I was in Japan with him in the past, and he swore an oath to serve our dynasty. Now that he is here, we can use him as a spy Jian (間): an operative used for internal subversion or espionage."

They then began plotting how to recruit him. They learned that Shimazu Yoshihiro original: "Yihong" (義弘) was still at Sacheon, in command of the Mangjin defenses.