What does it do?

It fires a projectile at a elevated angle (higher than 45 degrees) it falls from the sky and lands on your enemy.

How does it work?

Fires explosive projectiles known as (mortar) bombs at low velocities, short ranges, and high arching ballistic trajectories. Typically muzzle loading with a short often smooth barrel, generally less than 15 times its caliber.

Was it successfully used?

Yes it has been successful they have been using them for hundreds of years.