[Explanation]: A "brocade pouch" (jin nang) was a silk bag traditionally used to store secret documents or poems. In old novels, a wise and resourceful character would write strategic plans on slips of paper, seal them in a brocade pouch, and give them to someone so they could open and read the instructions in times of emergency. This idiom metaphorically refers to a clever, pre-prepared solution.
[Origin]: Ming Dynasty, Luo Guanzhong's "Romance of the Three Kingdoms," Chapter 54: "You will escort our lord to Wu. Take these three brocade pouches. Each contains a brilliant strategy; carry them out in order."
[Story]: After Liu Bei seized control of Jing Province, Zhou Yu, the great general of Eastern Wu, became determined to retake it. Hearing that Liu Bei's wife had recently passed away, Zhou Yu devised a plan: he would arrange for Sun Quan's younger sister to marry Liu Bei, inviting Liu Bei to come to Eastern Wu for the wedding. Once there, they would imprison him and use him as leverage to reclaim Jing Province. Zhuge Liang, foreseeing this plot, gave Zhao Yun, who was accompanying Liu Bei to the marriage ceremony, three brocade pouches containing secret strategies to be used in sequence.
The first strategy involved seeking help from Lady Qiao (mother of Sun Quan and mother-in-law of Zhou Yu), turning the fake marriage proposal into a genuine one and allowing Liu Bei to gain a noble bride. When Zhou Yu's plan to deceive Liu Bei with a "beauty trap" failed, he shifted to a real "beauty trap."
Zhou Yu then wrote to Sun Quan suggesting they instead "softly entrap" Liu Bei in Wu: "Build him magnificent palaces to dull his ambitions; shower him with beautiful women and fine luxuries to please his senses; separate him from Guan Yu and Zhang Fei, and cut off his connection with Zhuge Liang—place each in a different location. Then attack with our army, and our great cause will be accomplished." However, Zhuge Liang's second brocade pouch strategy foiled this real beauty trap. Citing a crisis in Jing Province, it used Lady Sun (Liu Bei's new wife) to petition the Empress Dowager, falsely claiming they needed to go to the riverbank to perform ancestral rites, thus enabling their escape from Eastern Wu. Although Zhou Yu had prepared for this, sending men to pursue them, the third brocade pouch strategy again used Lady Sun's authority to command the blocking troops to stand down. At this point, Zhuge Liang had already sent ships to rendezvous with them at Liu Lang Pu, and dispatched troops led by Guan Yu, Huang Zhong, and Wei Yan to repel Zhou Yu's pursuing forces.
Indeed, "Zhou Yu's brilliant schemes shake the world, yet he loses his bride and his soldiers!" Previously, at Nan Commandery, he lost a city and troops, which only caused anger and temporary frustration. But now, losing both the bride and the soldiers, he was overcome with both rage and shame, deeply wounded. Watching helplessly as Liu Bei and his wife safely returned home, how could Zhou Yu not be so enraged that his old wound burst open, causing him to faint?
The Three Brocade Pouch Strategies:
1. Seek out Qiao Guolao (Lady Qiao) and make Liu Bei's marriage widely known throughout Eastern Wu;
2. Use a lie (that Cao Cao is attacking Jing Province) to lure Liu Bei, who is immersed in marital bliss, back home;
3. Have Lady Sun use her royal authority to deal with the Eastern Wu pursuers, as the generals of Wu fear her, being Sun Quan's sister.