Models defending the walls against an assault may make a special Man the Walls! charge reaction. This reaction allows any unengaged models defending the ramparts to move up to 2" towards the enemy after the enemy has assaulted the walls and placed its models on the ramparts. This movement is done out of the normal movement sequence, immediately before the Close Combat phase. This rule represents the defenders throwing their forces against the enemy's assault. The troops may also use rocks or cauldrons of boiling oil (though not in assaults by siege towers).