The early modern discourse on battle painting, a recurrent topic in sixteenth-century artistic literature, revolved around how war should be correctly and effectively represented. According to contemporary sources, the main purpose of battle scenes was to solicit the viewer's participation and emotional response, to celebrate the fame of a war or even to entice to arm. Cinquecento art treatises therefore, harking back to the principles of Classical rhetorics, recommended that epic subjects be rendered with a forceful style that would persuade and move the audience with brilliance of skill and invention, and by virtue of its vividness (enargeia).
Around 1492 Leonardo addressed the same issue in a long and detailed passage written in his Manuscript A, fols. 111r-110v, that later his pupil Francesco Melzi transcribed in the Libro di Pittura (ch. LXVII). Even so, his notes on How to Represent a Battle tackle the challenge of depicting war in a peculiar way. Instead of dealing with the theme of the battle as a problem of composition and rhetorical decorum, or as a case of historical truthfulness and accuracy, as later Cinquecento art theorists would do, Leonardo foregrounds vision and its limits, seemingly turning the oscillation between the visible and the invisible into the subject of the representation.
Describing how the view of battlefields is always confused by mud, dust and smoke, Leonardo identifiesthe failing of sight as the defining experience of war, for both spectators and participants. The insistence on the actions and states of the eye is striking, and observations about the gestures of soldiers, struggling to restore their impeded sight, are often repeated and outlined in great detail.
The passage opens examining the visual effects created by the smoke of the artillery and the dust stirred up by the violent movement of the cavalry. Leonardo emphasizes that the further soldiers are placed within the swirling mass of fighting bodies, the less they are visible, as clouds of smoke and dust veil the pictorial field to the eyes of the beholder.
Combatants are characterized by an even more dramatic impossibility or unwillingness to see. Leonardo recommends depicting victors emerging from the multitude having ceased fighting, while wiping their eyes of dirt caked on their faces in a mixture of tears and dust. Reserve troops should be represented in search of orders from their commander, as they sharpen their eyes to survey the turmoil, bringing their hands to their foreheads to shade the eyes against the sun. Ultimately, vision becomes the hallmark of victory: while the conquerors try to recover their sight, those hopelessly caught in the middle of the struggle — Leonardo continues — will refuse to see. Wounded and vanquished, lying on the ground, they will shield their terrified eyes with one hand, raised with the palm turned outwards, toward the enemy.
The link between vision and conflict unfolds in different aspects of Leonardo's work. His studies on the physiology of the eye metaphorically associate battles with the process of vision itself, which Leonardo stages as an antagonistic confrontation between light and eye. In Manuscript D, a small notebook devoted entirely to optical studies datable around 1508, Leonardo explains that when the eye is "offended” by excessive brightness (offesa dalla soverchia luce, Manuscript D, fol. 5v), it contracts the pupil to protect itself. Incessantly vigilant, Leonardo's mobile eye moves constantly and swiftly to continuously adjust the pupil to different light intensities. A related diagram from Manuscript D (fig. 1)illustrates the phenomenon in greater detail, showing how the pupil's contraction (from nm to a) is able to temper the power of a luminous object placed in front of the eye. As a result, the image transmitted by the object through a system of radial emissions (qu) hits the curved surface of the eye with diminished magnitude (in ps rather then in r9).
However, the pupil's defense mechanism has its limits: for example,the eye can be assaulted and blinded by light due to the reaction time required by the pupil's contraction (Codex Forster 2.2, fol. 158v). Leonardo also observed how sheer brilliance impedes sight (la superchia luce l'impedisce la vista, Manuscript D, fol. 5r), and investigated the relationship between fully illuminated colors and the limited ability of the pupil to endure such brightness, ultimately associating sight with pain (Madrid Codex II and Manuscript E).
Likewise, in Leonardo's lost Battle of Anghiari, the depiction of the battlefield seems to be inextricably linked with ideas about the faculty of sight and its loss. Based on remaining copies, the design for the central group of the battle—the so-called Fight for the Standard— represented the struggle between four horsemen for the possession of a military banner (fig. 2). A minute but decisive detail placed at the center of the composition suggests how the action will unfold, as the rider on the far right will soon blind his opponent with the tip of his spear, causing the closely intertwined figures to disband. Once again, the eye and its defeat lie at the center of the narrative, as a fragile hinge on which the entire composition is precariously balanced.
The Fight for the Standard therefore acquires its narrative dimension only through a prolonged and attentive mode of viewing. Only the spectator who visually unties the knot of fighting figures by retracing their interlocking limbs —a spectator who partakes in the battle—is rewarded with an understanding of the action and how it will unfold. By forcing the eye to move across and around the tightly joined unit of bodies, Leonardo manipulates the process of looking, which he describes in Manuscript D as a constant shift of the natural axis. Enhancing thereby the natural motion of the eye, perception extends over time, securing the viewer's participation.
In Leonardo's battle scenes a physiological continuity links the process of visual perception to the subject of the representation: the encounter on the battlefield mirrors that on the visual field, where the eyes of the beholder are exposed to lusters and highlights, as well as to the rhetorical brilliance of the picture. The visual force of painted images can then be expressed in terms of physical as well as metaphorical light: as intense brightness moves the beholder's pupil, so his mind is moved—inflamed, aroused or scared—by the painting's enargeia, its brilliance of style and invention.
Fig. 1 Leonardo da Vinci, Eye Diagram, detail, Manuscript D, fol. 4r, Bibliothèque de l'Institut de France, Paris.
Fig. 2 Sixteenth-century Anonymous (retouched by Peter Paul Rubens?), Copy of Leonardo’s ‘Fight for the Standard’, Musée National du Louvre, Paris. (Scala / Art Resource, NY).