MCRP 12-10B.1, page 80

e. Time Available. The commander establishes priorities of work, which depend on the time available. Many tasks can be accomplished at the same time, but priorities for work are accomplished according to the commander’s order. An example priority-of-work sequence follows: Establish security and communications Assign sectors of responsibility, final protective fires Clear fields of fire Select and prepare initial fighting positions Establish and mark routes between positions (including alternate and supplementary routes) Emplace obstacles and mines Improve fighting positions. 3103. Organizing for a Defense a. Types of Defense. The defense of a built-up area should be organized around key terrain features that preserve the integrity of the defense and provide the defender ease of movement. There are two types of defense: position and mobile. (See MCWP 3-1, Ground Combat Operations [under development] for details on defensive operations.) Most defenses will include a combination of position and mobile defense. The type of defense chosen is predicated on commander's intent and METT-T. (1) Position Defense. The type of defense in which the bulk of the defending force is disposed in selected tactical localities where the decisive battle is to be fought. Principal reliance is placed on the ability of the forces in the defended localities to maintain their positions and to control the terrain between them. The reserve is used to add depth, to block, or restore the battle position by counterattack. (Joint Pub 1-02.) The position defense is usually characterized by defending key terrain. In the urban environment, this equates to the physical occupation of key public buildings, avenues of approach, transportation centers, industrial parks, etc. This defense focuses combat power to repel the attacker’s advance and/or penetration while retaining the terrain. This type of defense is common for battalion-sized units and below. The commander conducting a position defense organizes forces utilizes the same fundamentals that apply to any defense. Forces can be assigned sectors to defend and/or battle positions or strongpoints based on the commander’s analysis of METT-T. Reserves are identified and located to respond quickly to exploit success. Military Operations on Urbanized Terrain 3-9