Mercenaries and War: Understanding Private Armies Today

A couple of minor points: "Xenophon had a huge army of Greek mercenaries" is not really so. On the Anabasis proper, Xenophon was along as a tourist. After Cyrus was killed at Cunaxa, and the upper leadership captured and killed, Xenophon was elected one of the leaders for the march back to the Black Sea.

"Even Sir Thomas More, the great humanist and author of Utopia, coining the word, advocated using mercenaries to protect his utopian republic." Sort of. The narrator says that of the Utopians that "in great extremities or sudden accidents they employ [their treasure] in hiring foreign troops".