Recto: studies of soldiers and horses fighting; two figures of soldiers scrambling, with their backs to the viewer. Verso: a sketch of a sleeve and a woman's bodice. Melzi's number 109.

Leonardo’s most ambitious painting – albeit unfinished – was the Battle of Anghiari, a mural intended to be perhaps 60 feet (18 m) wide, depicting a celebrated Florentine victory of 1440 over the forces of Visconti Milan. The painting was commissioned in 1503 by the Florentine government for the Great Council Chamber of the Palazzo della Signoria. The painting was underway by June 1505 and proceeded until the summer of 1506, when Leonardo’s temporary return to Milan was requested by the French occupiers of that city, and permitted by the Florentine government for diplomatic reasons. Although Leonardo was back in Florence at least twice in 1507 and 1508, he never resumed the painting. Only the central portion, known as the Fight for the Standard, was substantially completed and this was obliterated – or, as has been claimed, concealed – after 1563.

RCIN 912330 and 912338 consider possible figures, horses and groups for the composition. This drawing is one of many small pen sketches for groups in the composition (others are in Venice, the British Museum and elsewhere), and emphasises that the horses were active participants in the battle. We see a rider raising his sword to strike a fallen horse (an unseated foe may be indicated at the centre of the group), and two ideas for horses fighting among themselves, kicking and biting. Two quickly sketched figures climbing over an obstacle link the sheet with the pen studies on RCIN 912328, the most diverse sheet of studies for the Battle of Anghiari.

Text adapted from Leonardo da Vinci: A life in drawing, London, 2018