In 1478 Leonardo had been commissioned to paint an altarpiece representing The Vision of St. Bernard for the chapel of San Bernardo in Palazzo della Signoria; before this, it had been commissioned of Piero del Pollaiolo. Leonardo did not finish the work, although he had prepared a cartoon. The commission was then assigned to Ghirlandaio, but it was Filippino Lippi who finished the work, now in the Uffizi. According to the Anonymous Magliabechiano, Filippino also used Leonardo's cartoon. Through a succession of iconographic transformations, it had become a Virgin enthroned with four saints and two angels that recall the angels of Verrocchio and Leonardo, as well as those created for the Forteguerri Cenotaph in Pistoia, now displayed at the Louvre.
In 1503 Leonardo was commissioned to paint, for the Great Council Hall in Palazzo della Signoria, a grandiose wall painting representing the Battle of Anghiari, in commemoration of the victory won on June 29, 1440 by the Florentines under the command of Giovanni Paolo Orsini over the Milanese led by Niccolò Piccinino. Plans called for another great painting on the opposite wall, a Battle of Cascina for which Michelangelo was chosen.
The payments recorded in the archival documents include costs incurred for building the mobile scaffolding and for recompensing Leonardo and his assistants. Interesting in this regard is an autograph note by Leonardo found in Madrid Ms. II. On Friday, June 6, 1505 he was in Palazzo Vecchio and at the hour of one o'clock he began to paint on the wall of the Great Council Hall: «On the day of June 6, 1505 a Friday, at one o'clock precisely, I began to apply the colours in the palace. As I was about to use the brush, a storm broke and thunder pealed, summoning men to reason. The cartoon was torn, water gushed in, and the jar of water we had brought was broken. And immediately the weather turned foul and rain poured down until evening. And it was dark as night.»
Some questions are posed by this passage. Were these his first brushstrokes or, as is probable, a resumption of work? Does this recollection express a sad premonition? The rhythm of the wording is pressingly urgent. Is it possible that the words «the cartoon was torn», «water gushed in», «the jar was broken» held prophetic significance for Leonardo? Along with «the weather turned foul and it was dark as night», was it a premonition of that legendary ruin of the painting which, according to the Anonymous Gaddiano and Vasari, was to destroy the nascent masterpiece of Leonardo?
The most likely hypothesis is that it was not a matter of the whole painting deteriorating, but rather of a partially negative result at a preliminary stage. Could it be instead that Leonardo interrupted his work to go to Milan at the request of Charles d'Amboise and King Louis XII – as wrote the Gonfaloniere Soderini – after having «made a small beginning on a great work»? And is it not documented that on February 26, 1513 (1514 according to the Florentine calendar) a wooden structure was built «to be placed around the figures painted in the Great Hall of the Guard by the hand of Lionardo da Vinci, to protect them, so they will not be damaged»? It thus seems that Leonardo's unfinished masterpiece was not only conserved and well protected, but even visible and highly esteemed. Significant in this regard are the words written by Anton Francesco Doni in 1549, years before Vasari's restoration initiative (1563): «And having climbed the stairway to the Great Hall, diligently observe the group of horses and of men (a battle scene by Lionardo da Vinci) that will appear to you a marvellous thing indeed». It is hard to believe that Vasari would have destroyed a masterpiece by Leonardo. It is much more probable instead that he covered it with his own frescoes. As of now, scientific examination and on-site research have not yielded the expected results, but investigation is still going on.
Other doubts arise as the fate of the "sumptuous" cartoon still remembered in the 18th century, and the possible collocation of the preparatory panel that was undoubtedly painted (as proven also by the engraving made by Lorenzo Zacchia in 1558).