During the course of the eleventh and twelfth centuries, walls became higher and thicker, often sloping out at the bottom to counter attacks with battering rams. The parapet on the outer side of the walk along the top of the wall was notched with crenellations—that is, crenels (low walls) alternating with merlons (higher walls), behind which men on the wall-walk could seek protection (see the crenellated wall-walk at Aigues Mortes, Figure 22). The merlons could be pierced with arrow loops, holes through which archers could shoot while still being protected by the merlon. Such walls did not permit adequate observation or defense of the entire wall, because the men could not see the bottom of the wall without leaning over the crenels and exposing themselves to the enemy’s death-dealing arrows and rocks. The addition of towers built out in front of the wall and galleries over the top of the wall solved this problem. The wall-walk could be developed into a full-scale fighting gallery. Temporary wooden galleries, known as hoardings, doubled or tripled the space available for the defenders at the top of the wall (see Figure 12). Beams or brackets supported the hoardings and permitted holes in the floor through which the defenders could observe the wall and its base, shoot their arrows, or drop stones and other missiles. Brief forays (sallies) outside the walls helped to keep up the defenders’ morale.