One thing Leonardo da Vinci may have understood better than any of his contemporaries was the psychological effects of weapons in warfare. Da Vinci knew that the fear weapons could instill in enemies was just as important (if not more so) than the damage they could actually inflict.

This was one of the main ideas behind many of da Vinci’s war inventions – among them, his giant crossbow. Designed for pure intimidation, da Vinci’s crossbow was to measure 42 braccia (or 27 yards) across. The device would have six wheels (three on each side) for mobility, and the bow itself would be made of thin wood for flexibility.

Rather than fire giant arrows, Leonardo’s crossbow instead seems to be designed to fire large stones or possibly flaming bombs. For use, a soldier spins a crank to pull back the bow and loads the artillery. The soldier would then use a mallet to knock out a holding pin and fire the weapon.

The giant crossbow invention is a great example of the way da Vinci’s artwork really brought his ideas to life. Through his illustrations, an idea, however improbable, becomes realistic and plausible. His vivid drawings of the giant crossbow invention also make it clear the idea behind the impressive weapon was to terrify enemies into fleeing rather than fighting.

For more information on Leonardo da Vinci’s giant crossbow invention, please visit:

Science and Society Picture Library
BBC Science & Nature – Leonardo, Giant Crossbow