During the reign of Emperor Ming of Wei, Cao Rui, the warlord Gongsun Yuan held sway over Liaodong and defied central authority. Cao Rui ordered Grand Commandant Sima Yi to lead an army to subdue Liaodong.
Before departing, Emperor Ming of Wei discussed the campaign with his ministers in the court. When asked about the estimated duration, Sima Yi replied, "One hundred days for the journey there, one hundred for the return, one hundred for the assault, and about sixty days for rest—a year should suffice." The emperor then decided to dispatch forty thousand troops, but many officials argued this was excessive, warning that supplying such a force would be too costly. Emperor Ming firmly declared, "The march is four thousand li long. Though the expense is great, it must be provided—we cannot be overly frugal."
When Sima Yi led 40,000 troops to Liaodong, he was met with relentless rain that prevented an immediate assault. Court officials buzzed with debate, arguing that Gongsun Yuan could not be swiftly crushed and that Sima Yi should be recalled. Emperor Ming of Wei dismissed their concerns, declaring, "Sima Yi is resourceful and cunning—he will adapt to circumstances, overcome the crisis, and capture Gongsun Yuan in a matter of days."
Soon after, Sima Yi indeed defeated Gongsun Yuan and sent his severed head to the capital, finally pacifying Liaodong.
Later, the idiom "Counting the Days" came to describe a wait so short you could count it on your fingers, meaning the time is not far off.
Source: *Records of the Three Kingdoms*, "Book of Wei: Biography of Emperor Ming"
Meaning of the Idiom: Later, the Chinese idiom "计日可待" came to describe a wait so short you could count it on your fingers, meaning the time is not far off.