From the Introduction:
Siege towers, another kind of specialized siege engines to put fear in the hearts of the defenders on a wall more importantly to get the attackers on or across said wall. Taking a lot of resources and just as much time to construct siege towers are often a last resort to breach walls that could not be brought down with catapults or stormed using simple ladders.
One such tower is approaching this section of a city wall. The moat surrounding the wall has already been filled in and it is now only a matter of time until the tower reaches the wall and spews hordes of attackers onto it. The tower itself is a rather simple and rushed construction.
Made entirely from wood it lacks fire proof plating and it sports no artillery of its own. Its wooden planks are nonetheless capable of protecting numerous archers, pike and swordsman form arrows and crossbow bolts that might be fired from the walls.