Like the AKM and a few other weapons, the mortar has been featured in every Rambo film after the first one.
First introduced in the Middle Ages, a Mortar was one of the three main artillery weapons of the time. The heavy duty weapons of the time included catapults, mortars and cannons, among countless other weapons, such as cauldrons for boiling oil and battering rams. The cannon was designed to fire heavy metal projectiles at walls and destroy them. However, the castle walls proved to be so thick that the cannons were not doing the job properly. So, the mortar was invented by combining the cannon and the catapult. The cannon was tilted on its back and fired straight in the air so the projectile would arch over the castle walls and destroy the castle itself from the inside. The mortar was a deeply feared and powerful weapon because there was no way you could protect yourself from it.