While Leonardo Da Vinci did not invent the mortar, it was an extremely significant piece of weaponry. Early mortars were used to lob exploding projectiles over fortress walls or into enemy cities. One of Da Vinci's sketches depicts using mortars with fragmenting and exploding fire bombs. This type of projectile not be used until the late 1600s, many years after Da Vinci imagined them. These mortars also implement the elevation mechanism present in his cannon designs. 

A second revolutionary design by Da Vinci was the "machine gun", his vision of a superior cannon. His sketches show a specialized aiming mechanism with a fan-shaped spread of small barrels capable of firing in multiple directions at once. Another sketch consists of 33 short barreled guns in rows of 11 mounted to a cart.  Unlike traditional cannons, these smaller barrels resemble traditional guns, however they are mounted to a frame that should be lightweight and more maneuvarable than cannons. Da Vinci realized the importance of speed and agility in warfare, inspiring him to design relatively slim and nimble weapons that could be loaded and fired quickly. World History Project says this about Da Vinci's machine guns, “[Leonardo] wanted to increase the rate of firing weapons and so designed machines with multiple cannons, so they could be fired successively or all together. Many people consider these the forerunner of the modern machine gun. Two of these used racks of eleven or fourteen guns. While the top row was being fired the next rack was loaded; at the same time, a third rack was cooling off. Another design had the guns in a triangle spread for greater distribution of the projectiles."  Da Vinci was correct in his designs, as mortars and cannons would be the driving force behind invasions for centuries to come. 

Sources:

“Mortar (Weapon).” Wikipedia, Wikimedia Foundation, 17 Feb. 2018, en.wikipedia.org/wiki/Mortar_(weapon).

Image Source:https://www.1000museums.com/art_works/leonardo-da-vinci-sketch-of-a-mort...

“Machine Gun.” Machine Gun by Leonardo da Vinci, www.leonardo-da-vinci.net/machine-gun/.

“Leonardo da Vinci Sketches the Design for a Machine Gun.” World History Project, worldhistoryproject.org/1500/leonardo-da-vinci-sketches-the-design-for-a-machine-gun.