What defensive vehicle did Leonardo da Vinci sketch with sloped armor and internal wheels?

Leonardo da Vinci sketched an armored vehicle with sloped armor and internal wheels.

The design appears in Leonardo's notebooks from the late 15th century. Its conical covering was intended to deflect incoming projectiles, while several crew members inside would turn cranks connected to the wheels. The vehicle also showed openings for weapons around its perimeter.

It is often called Leonardo's tank, but that modern label can obscure its historical character. The machine was not a powered tank in the 20th-century sense: it had no engine, tracks, or completed battlefield record. Some reconstructions also identify a likely gearing problem that would make the drawn vehicle move in the intended direction difficult.

The sketch illustrates Leonardo's approach to military engineering, combining protection, mobility, and concentrated firepower. Whether it was a serious proposal, a demonstration model, or a deliberately flawed design remains debated, but the surviving drawing clearly shows an armored fighting vehicle concept.