“These elephant-mounted cannons deal good damage to buildings from a safe distance. They're more durable than regular siege, though still vulnerable to enemy troops. They're more durable than regular siege, though still vulnerable to enemy troops.”
Elephants acted as a kind of heavy tank for the ancient world. During the late 16th century culverin (light cannon) and jingals (swivel-mounted guns) were mounted on elephants as militaries sought to adapt the elephant to use during the gunpowder age. Unfortunately this same technology would inevitably drive elephants from the battlefield by the 19th century, restricting them to engineering roles.