Final answer:
Da Vinci served as a military engineer designing various military devices, which is evidenced by his work on inventions like the military tank and giant crossbow.
Step-by-step explanation:
Yes, Leonardo da Vinci did work for the military. Specifically, he worked as a military engineer. He used his skills and knowledge in various areas of engineering and science to design military machines such as a flying machine, a tank, and a bridge. His expertise in military engineering is evident in the design of a giant crossbow that he created.
Leonardo da Vinci, a renowned figure of the Renaissance, worked not only as a painter but also extensively as a military engineer. He had offered his services to Ludovico Sforza, Duke of Milan, where he listed his various skills which notably included the design and creation of military devices such as bridges, fortresses, and siege equipment. The designs for a helicopter-like flying machine, a military tank, and a giant crossbow are testament to Leonardo's contributions to the military engineering field, showcasing his integration of scientific inquiry with engineering design.