Their main function is to defend against arrows and stones.
The arrows shot by those giant spirits have a minimum power equivalent to the four-armed giant crossbow of the Human Clan. Moreover, their numbers are in the thousands, continuously and relentlessly raining down from all directions.
As for the stones, their power is significantly greater than the catapults of the Human Clan. Those stones, as large as millstones, crash down like raindrops, with overwhelming momentum.
The soldiers from the Ice State built the wooden walls extremely thick, using seven layers of towering giant trees, with a large pile of stones behind them. Yet, after a ten-hour siege, these wooden walls have been riddled with holes and are on the verge of collapse.
Those trenches don't offer much defense either, merely preventing the giant spirits from crossing with a few strides and jumps to reach their campfront.
This defense structure is considered simplistic, yet it is the best they could achieve.
