Fortins were redoubts established in strategic places. Depending on the importance of these small forts, they contained from ten to one hundred men and could be reinforced by garrison towns at the back. They were made of a large square tower with a brattice (small rectangular lodge overhanging the frontage) at the entrance, allowing to throw out projectiles onto the enemy. The first level loopholes gave the possibility to aim at the base of the building and on top of its surrounding wall. Their structure is almost similar to the towers of the Shanxi region. The roofs were arched: a technique widely used for the Great Wall. Those bastions contained all the rations for the surrounding warriors. They were often surrounded by houses and therefore, looked like small towns. In more critical areas, fortins could reach the size of a fortified castle.   + photo ...