Fire Nation battlements are small tower-like structures that house firebenders and ballistae, large crossbow-type weapons. There are usually at least two soldiers at each battlement. The crossbows fire spears, which are attached to chains; if they puncture the hull of a boat, the chain is drawn back to pull the vehicle right out of the water, making it vulnerable to attack by soldiers. However, the chains are relatively weak, as Katara was able to cut one of them with just one swipe of water.