What vehicle did Leonardo da Vinci sketch that is often called the first modern tank?

Leonardo da Vinci sketched an armored vehicle, a conical war machine often described as an early tank concept.

The vehicle was designed around a broad, sloping shell that could deflect incoming shots. Small cannons were arranged around its lower edge, while people inside would turn cranks connected to wheels. Leonardo prepared the design in the late 15th century for Ludovico Sforza, the ruler of Milan, as part of a portfolio of military engineering ideas.

It was not a modern tank and was never built in Leonardo’s lifetime. The surviving drawing also appears to contain a mechanical inconsistency: the gears would make the wheels turn in opposite directions. Some historians think this may have been deliberate, but the exact reason remains uncertain.