In 228 AD, Zhuge Liang launched another campaign from Qishan against the Wei kingdom, but his disastrous choice of Ma Su to defend the strategic Jieting Pass led to its fall, forcing him into a desperate retreat to Xicheng.
Soon, Wei's Grand General Sima Yi led 150,000 troops charging toward Xicheng. At that time, Xicheng had only 5,000 soldiers, and half of them had already been sent to transport grain, making the situation extremely critical.
Facing an overwhelming enemy army at the city gates, with no strength to resist and no time to flee, Zhuge Liang ordered, "Lower all battle flags from the walls. Every officer must hold their post without the slightest panic—anyone who disobeys will be executed immediately."
He then ordered the city gates thrown wide open, selected several dozen veteran soldiers disguised as commoners to sweep the streets near the gate without showing any panic, and finally ascended the gate tower to sit upright, burn incense, and play the zither, feigning complete composure.
When Sima Yi led his massive army to the gates of Xicheng, he was stunned to see Zhuge Liang seated calmly atop the city wall, burning incense and playing the zither with a serene smile, two young attendants by his side, while a dozen commoners swept the ground inside and outside the gate as if no army were approaching. Sima Yi listened closely to the music; its notes were filled with confidence, not a trace of panic. Suspecting a hidden ambush behind the walls, he dared not attack and immediately ordered a retreat.
Zhuge Liang breathed a deep sigh of relief as he watched Sima Yi retreat, then calmly led his troops out of Xicheng.
Later, the idiom "smile beaming" came to describe a face so full of smiles it seemed one could cup it in both hands.
Source: *Romance of the Three Kingdoms*
Meaning of the Idiom: Later, the Chinese idiom "笑容可掬" came to describe a face so full of smiles it seemed one could cup it in both hands.