Why mince words? The 1502 scheme concocted by Leonardo da Vinci and Niccolo Machiavelli — a rare case of collaboration between geniuses of the first order — proved an utter fiasco.

Their plan was to divert the Arno River, depriving Pisa of water and thus compelling its surrender to the besieging Florentines. It ended up yielding a lot of mud, at great cost to Florence and to the careers of its planners. Leonardo left town, never to work there again, and Machiavelli was soon driven from politics to write the works that have immortalized him. And that was that: a footnote to history, interesting, yes, but primarily because this odd couple of bunglers bore such famous names.