On the ancient battlefield of the Central Plains during the Warring States period, after a bloody slaughter, an old man with white hair and beard was bent over, carefully examining the faces of the dead. He had been searching for a long time—he was looking for his son's body. A man from Wei, his son had been a soldier in the Wei army. Five days earlier, when the Qin army invaded, the King of Wei ordered a counterattack. Before leaving, his son rushed home to say goodbye, explaining that the troops were heading to Shangjun. He didn't even have time for a meal before departing.
He left and never returned. The Battle of Shangjun turned into a bloodbath, with corpses strewn across the fields and all thirty thousand Wei soldiers dead. The Qin army seized Shangjun, looted every village, and captured the elderly and weak, tying them with ropes and marching them single file toward the Qin camp. The old man had escaped the night before, slipping away while the Qin guards were careless.
By midday, the old man found his son's head, already severed from the body, a right ear and half the face sliced off by a blade, the blood long dried. Yet it was such a familiar face—no mistake, it was his son's. But where was his body? How alike those headless corpses looked! The old man thought for a moment and decided to first identify the body wearing the "Wu Zu" armor, then check for the blue birthmark on the lower back. So he turned over more than twenty similar headless bodies, each time wiping away tears to steady his gaze, trembling with heartache. After a pause, he persisted in his search, and finally by a marshy patch of weeds, he recognized his son's birthmark. There it was! His poor son—his abdomen had been cut open, intestines spilling onto the ground. The old man placed the head and body together, unable to hold back his tears, and wept aloud.
The people of Wei and Han, who did not curse the brutal Qin state? From Duke Xiao of Qin to King Zhuangxiang, six generations of rulers over a hundred years ceaselessly waged war on their eastern neighbors, with Wei and Han bearing the brunt as countless lives were lost in battle. The same tragedies played out repeatedly on the battlefield. Jia Yi said, "A million corpses lay strewn, shields floating in rivers of blood," which may be an exaggeration, but Lord Chunshen's account—"Heads and bodies separated, bones bleaching in the wilds, skulls piled high across the land"—was a true depiction. The calamities war brought upon the people were endless.
Later, the idiom "head and body separated" came to refer to decapitation.
Source: *Strategies of the Warring States*, Chapter "Strategies of Chu"
Meaning of the Idiom: Later, the Chinese idiom "身首分离" came to describe how head and body separated came to refer to decapitation.