Katapult (Civ4 FFH)
This is a basic siege weapon; use it to lessen or remove city defenses, preferably with one or more strong defensive units in a strong defensive position. They can also be used to attack stacks, but note that their limit is at 50%.
The catapult was one of the earliest forms of artillery. It was a large mechanical arm that propelled heavy stones and other missiles from a great distance, battering down walls and inflicting damage on buildings and defenders. Catapults could easily launch projectiles 500 to 1000 feet with a surprising amount of force behind them. Though cumbersome and nearly useless on the battlefield, the catapult was an effective weapon for siege operations.
A Catapult can bombard enemy city fortifications and has a chance to withdraw from combat when losing. When attacking another unit, they cause collateral damage to other enemy units sharing the target's space.