In Thomas Malory’s Le Morte d’Arthur, the legendary King Arthur had to confront the errant Mordred at Camlann. The two entered tense negotiations while their uneasy armies stood by, ready for the least sign of aggression from the other. One knight, however, was walking in the grass and came across an adder. He pulled out his sword to kill the snake and two armies took that as a signal. The resulting carnage was – literally – almost total.
