What was the protective military vehicle in Leonardo da Vinci’s 1487 design commonly called?

The protective military vehicle in Leonardo da Vinci’s 1487 design is commonly called Leonardo’s tank.

Leonardo designed the fighting vehicle while seeking employment from Ludovico Sforza, the ruler of Milan. His proposal described a conical, armored vehicle fitted with guns around its perimeter. The sloping outer shell was intended to deflect incoming projectiles, while the vehicle’s crew could fire from protected positions.

The machine was meant to move using cranks connected to wheels. Some modern commentators point out that the gear arrangement shown in the drawing would make the vehicle difficult or impossible to propel as depicted. This may have been an error, a deliberate flaw to protect the design, or simply an unfinished engineering solution; the evidence does not establish Leonardo’s intention.

No Renaissance example is known to have been built. The nickname “tank” is modern and should not be confused with the tracked armored vehicles developed during the First World War. Leonardo’s design was an armored fighting vehicle concept, not a working tank in the modern military sense.