6-176. When a commander directs a mobile defense, subordinate units conduct either an area defense or a delay to shape the penetration of the enemy attack as part of the fixing force. Operational-level commanders do not assign the mission of a mobile defense to subordinate units smaller than a division because of their lack of resources. Dynamic movement from battle position to battle position characterizes a mobile defense. A commander may direct a BCT to conduct a delay as part of the division mobile defense.