The Battle of Anghiari

Leonardo never completed the commission and left the work unfinished in 1505. According to an early biographer, Leonardo had experimented working in a different fresco technique involving walnut oil but the colors were too unstable, leading the master to abandon the project. Leonardo's unfinished work remained on site for a while and was admired by many visitors and artists; it was ultimately destroyed and replaced by a new work (today, Giorgio Vasari's frescoes from 1563-65 can be seen in its place).

Many preparatory studies by Leonardo still exist. The composition of the central section is best known through a drawing which was made in the 16th century and later acquired by Peter Paul Rubens who extended the edges of the drawing. The drawing is in the collection of the Louvre in Paris, where it is referred to as The Battle of the Standard. This drawing succeeds in portraying the fury, the intense emotions and the sense of power that were presumably present in the original painting. Similarities have been noted between this Battle of Anghiari and the Hippopotamus Hunt painted by Rubens in 1616.

In March 2012, a team led by Maurizio Seracini announced that they had found evidence that the painting still exists on a hidden inner wall behind a cavity, underneath a section of Giorgio Vasari's fresco in the chamber. The search was discontinued in September 2012, without any further progress having been made, due to conflict among the involved parties.

In 2020, a group of art historians submitted the findings of their research on the work. Their conclusion was that the work had never been commenced or executed because Leonardo could not have created the painting as his proposed gesso and oil technique for making the layer for the painting would not have allowed the paint to attach to the wall.