In 413 BCE, outside Syracuse, the Athenian general Nicias, old and mortally ill, tried to rally the spirits of his defeated troops before their final retreat. A city, he told them, consists of its men, not of its walls or its empty ships. He had in mind their own city of Athens. In 480-79 BCE, about a decade before Nicias was born, Athens had been systematically sacked and burned, not once but twice, by Xerxes' invading Persian army; yet its citizens survived, against apparently insurmountable odds, to inflict crushing defeats on the invaders, first by sea off Salamis, and the following year by land at Plataea in Boeotia.