On Leonardo's return to Florence, around 1500 he discovered a Republican city with plans to commemorate a great Florentine victory over its bitter rival Milan. On June 29th, 1440, the mercenary commander Niccolo Piccinino attacked the papal troops of Florence at Anghiari.
Piccinino lost the battle and the new Republic of Florence chose the victory as a fitting subject for the decoration of their new council chamber in the Palazzo Vecchio.
Leonardo secured the contract for the painting in the Autumn of 1503. The young Michelangelo was commissioned to do a version of an equally famous battle, The Battle of Cascina, marking the Florentine victory over Pisa in 1364.
This was the only time these two renaissance giants were in direct competition with each other.
The scale of the Battle of Anghiari was impressive, a huge 54ft by 21ft (16.7 by 6m) incorporating three continuous scenes the beginning, middle and end of the battle. Leonardo certainly completed at least part of the work, the much copied central battle scene of colliding horses and cavalry.
These two studies illustrate the detail and preparation that Leonardo lavished on this work. The expressions of the two soldiers can be clearly identified, even in the copy by Rubens.
Leonardo worked on this project with his two assistants Raffaello d' Antonio di Biagio and Ferrando de Llanos throughout the first part of 1505. Leonardo left Florence for Milan in May 1505 and the work was abandoned.
The parts that had been completed were protected by wooden boards but the painting was finally lost in 1560 when Vasari re-decorated the chamber with his own frescoes, forty-one years after Leonardo's death.