Sarah Dunant at Literary Review:
Federico is a figure well worthy of attention. Born on the wrongish side of the blanket in 1420s (it was a crowded part of the bed at that time in Italy), he became ruler of Urbino in his early twenties after the assassination of his unpopular half-brother. While there is no evidence that he was involved in the plot, he was hovering conveniently nearby when it happened. The citizens who approached him to take over presented him with a list of unnegotiable demands, the most stringent of which was to abolish a set of recently introduced taxes and promise not to impose new ones. In itself, this was an impressive demand in a country filled with minor despots. Even more impressively, Federico kept his word.
His solution? To earn an alternative fortune from war. ‘Mercenary’ is a dirty term now, but it once stood for an honourable and highly lucrative line of work: selling your military expertise and soldiers to the highest bidder in a country made up of city-states and power blocs, such as Naples, Venice and the papacy, all of which needed to field armies.