Once lived a beautiful witch named John. He brought blessings on his community and interceded with the spirits on behalf of his people. Those who knew him loved him well. A great warchief, on his way to war, spotted John and coveted him. He approached him, though the witch was happily bound to another.
"Come away with me," said the general. "Every town I conquer, every army I defeat, will be in your name."
"You bring death wherever you go. I will not share that burden."
"If I cannot glorify you with blood, I will remember you with yours." The warchief raised his axe.
"My death will always haunt you," John said, and the general struck him dead.
John's cloak fell empty to the ground, and a dozen black birds flew into the sky. The thirteenth stayed with the witch's grieving lover. The rest followed the general. Feeding on the corpses he left behind, they grew into a great flock. The general never forgot the beautiful witch, to the day he died on his own battlefield. That day, the birds picked his bones clean.
That is why crows follow battlefields, and why a group of crows is called a murder.