Cao Cao was one of the central figures of the Three Kingdoms period. It was he who laid the foundations for the state of Wei and was posthumously titled Emperor Wu of Wei. Cao Cao has also been praised as a brilliant ruler and military genius great at leading troops in battle.
In 197 summer, Cao Cao was leading his army in a punitive expedition against a minor warlord named Zhang Xiu. It was terribly hot; the sun was sizzling the land; Cao Cao's soldiers braved the scorching heat, walking on the winding and treeless mountain paths. They were exhausted and extremely thirsty.
Seeing the marching speed had slowed down a lot, some civil officials suggest letting the troops take a rest, but Cao Cao and his generals disagreed, for they thought it was very dangerous to stay at a vulnerable place like that. Cao Cao called the guide and asked him on the quiet whether there was a source of water nearby. The guide shook his head, saying that the spring water was far away on the other side of the mountain.
Hearing this, all soldiers felt greatly bucked at once. Especially when they thought of the sour and juicy green plums, their complaint of thirst was quickly faded, and some soldiers' mouthes were even unintentionally full of saliva. As a result, they marched vigorously again. A short time later, they reached a safe place and found water.
Background and Writer Comment:
This Chinese idiom story is from "Shi Shuo Xin Yu (世说新语)", a book of collecting anecdotes, written by Liu Yi Qing of the Southern Dynasties period (420-589).
The idiom of "Satisfy Thirst By Watching Plums" refers to trying to console someone with false hopes.