Leonardo da Vinci’s circular, sloped-plated military machine is an armored vehicle.
Leonardo designed the fighting vehicle as a covered, conical structure with armor plates set at angles. Several crew members inside would turn cranks connected to wheels, theoretically moving the vehicle across a battlefield while its weapons fired through openings.
The sloping armor was intended to make incoming projectiles glance away rather than strike a flat vertical surface. The design also included space for guns around the platform. Historians and engineers have debated practical details, including whether the surviving drawing contains a gearing error that would prevent movement as shown.
The machine is often called Leonardo’s tank, but that is a modern nickname. It was not a modern armored tank with an engine, rotating turret, or track system. It was a Renaissance proposal for a protected, wheeled fighting vehicle.