This essay aims to investigate the critical history of Leonardo's Battle of Anghiari, commissioned by the Florentine Signoria to be realized in the Great Hall (today Salone dei Cinquecento) of Palazzo Vecchio in competition with Michelangelo's Battle of Cascina. Thanks to some contemporary and trustworthy sources, this paper demonstrates it is highly unlikely that this work of Leonardo had been actually realized since he could not had gone beyond the design phase of his project. This was caused by his experimentations on colors, and on the difficult technique of spreading an oil painting on a wall.