Catapult
From King Arthur's Gold Wiki
The catapult is the largest of the structures in the game. It can be constructed out of wood by the miner.
To build it just place the pieces and when the catapult is finished it is created and turned the right way.
To use it, press and hold "e" to aim. The longer you hold the further you shoot. The shots are aimed with mouse. Release "e" to shoot.
Gameplay tips
The catapult fires three stones at a time and can be very deadly. A well placed catapult can keep the enemies at bay even when outnumbered.