What is the content of the Vietnam War poem "You didn't come back"?

A shell pierced the silence of the night and took away the innocent living beings who were sleeping. People who wake up in fear find that dawn has opened its ferocious eyes and its desire has filled its fragile body. People have become meat-grinding machines. Tanks spewed out columns of hatred and ran over mutilated bodies. Thick smoke mixed with foul blood gas, countless blood rivers of humble life sleep all over the mountains and make the sunset more enchanting. The world has become purgatory, the smoke has dispersed, and people have found happiness again. People who love to laugh and forget leave history to books, and everything is calm again, but who are the blooming flowers beside the crater crying for?