A fixed Mortar built on top of the house can be used to directly target and fire with the range of 100m at attackers during a siege. You don't select the distance with the mouse wheel like other mortars, you simply aim and click on your target. The fixed mortar is NOT affected by wind, allowing for precise shelling. The mortars must be placed in the Emplacement House's inventory where they stack. With 5 slots, you can theoretically store 500 shells in it.