Approach trenches toward the enemy should be blockaded and hand and rifle grenadiers posted to guard them. The main captured trench should be converted at once into a fire trench facing the enemy. If it is badly knocked to pieces, a new trench may be constructed 40 or 50 yards in front of the captured line. The commander must reorganize in depth to provide supports and reserves for counterattacks. Situation reports should be sent back frequently. Rough sketches are better than messages. Tanks follow infantry as closely as possible to deal with strong points. They are employed in sections of four. Machine guns may be used to provide covering fire for attacking infantry, cover its withdrawal if the attack fails, fill gaps in the assaulting lines, assist in the consolidation of positions and repel counterattacks. Lewis guns are of great value in knocking out hostile machine guns. They usually move on the flanks of the second wave of assault. Later they are used to back up patrols and to hold the outpost line while the garrison line is being consolidated. As soon as consolidation begins, wire entanglements should be constructed. Every effort should be made to secure the objective against recapture. Any men available should be used to continue the offensive. All commanders down to and including company commanders must keep some portion of their command as a reserve. The company commander needs his reserve to work around points which are holding against the leading lines, to protect his flanks in case the companies on his right and left are delayed in their advance and to exploit his success and gain ground to the front. He must keep it well in hand behind the company. Battalion reserves must start with the assaulting column and get across "No Man's Land" as soon as possible; they must not get out of hand. Such a reserve is usually checked in the vicinity of the enemy's front line trench, where it can be thrown in to assist the advance or extend a flank as needed. The brigade reserve is kept well in hand just clear of the friendly front line and support trenches. Reserves of companies and battalions must start moving over the top of the ground with the rest of the assaulting troops.