What type of protective fighting vehicle did Leonardo da Vinci sketch for the Duke of Milan?

Leonardo da Vinci sketched an armored vehicle as a protective fighting machine for the Duke of Milan.

The vehicle was designed as a covered, conical structure mounted on wheels. Its sloping outer shell was intended to deflect incoming weapons, and openings around the perimeter allowed soldiers to fire guns while remaining partly protected. The machine resembles a low, armored platform rather than a modern tank in its technology or battlefield role.

Leonardo included the design in a letter to Ludovico Sforza, offering military engineering services. The letter presented him as capable of designing bridges, fortifications, artillery, and other machines. The famous drawing is usually dated to around 1487–1489.

A well-known feature is a gear arrangement that appears to make the vehicle impossible to drive. Historians commonly interpret this as either a deliberate security measure, an error in the drawing, or an omitted detail. Modern reconstructions have altered the gearing and shown that a version could move. Leonardo’s machine was never built for Renaissance warfare, so it is best understood as a design concept rather than an operational tank.