The Toys of War — George Herman

The brutal "execution" of the patriot woman of Faenza, Diamante, in violation of the laws of sanctuary, creates a division between Cesare Borgia and his sinister condottieri. Maestro Leonardo da Vinci, quietly attempting to reconcile his new profession as engineer to Cesare Borgia, with his philosophy of non violence is caught between the factions. When a sentry is strangled by a "man with strong hands," and two of the condottieri are murdered with Leonardo's own "toys of war", a wedge is driven between the artist/engineer and his patron, an alienation that could prove fatal to Leonardo.
Placed under guard by Cesare, the maestro manages to send word of his plight to Niccolo of Pavia, now a Bergamini courtier. Niccolo, enlists the services of the traveling commedia dell'arte players known as I Comici Buffoni, and together they gather the information and evidence that could prove Leonardo's innocence and expose the plot behind the murders.
What they learn brings Leonardo and Niccolo to the little Adriatic port of Sinigaglia, where a trap is sprung, a trap that Paolo Giovio called "il bellissimo inganno" -- the "magnificent deceit." Here, too, Leonardo comes to realize that the real "toys of war" are not the battle weapons he designs for Cesare, but something much more repugnant and horrifying!