The selection of the sites for the emplacements should be made with a view to bringing a powerful enfilade or oblique fire on the attacking enemy at effective range, to provide a flanking fire for supporting troops, and to sweep gaps in the line of obstacles. [Illustration: _From World’s Work._ PLATE 26.—Profile of type of cover for machine gun.] [Illustration: PLATE 27.—Type of cover for machine guns.] Their fire should come as a surprise to the attacking party. In the construction of cover for machine guns the following points should be observed: 1. They must have a platform for the gun and gunner. This may be provided for in the construction of the emplacement or built up with sandbags. The platform should be 3 feet wide and 6-1/2 feet in length. 2. If head cover is provided, it should not differ in appearance from that constructed elsewhere in the trenches. The loopholes must be blinded with gunny sacks. 3. The front of the emplacement should be cut under to receive the leg of the tripod, thus bringing the gun up closer to the parapet and furnishing more cover for the gunner. 4. Splinter-proof shelters should be provided near at hand for the members of the gun detachment. 5. Where the enemy’s trenches are near, the position for the emplacement should be selected by day and the actual work done under cover of darkness. 6. The guns should be located so that they support each other by their fire. Alternate positions should be constructed. 7. When located to enfilade straight lines of trenches, special capioniers should be constructed. [Sidenote: Supporting Points] At intervals from 800 to 1,500 yards along the first line, supporting points are established. They may consist of a fortified village or a specially prepared position having a “labyrinth” of trenches and rendered well nigh impregnable to infantry assault by every defensive device known to modern warfare. They are designed to bring a flanking fire to bear upon the intervening intervals with the idea that troops cannot pass beyond them until they are reduced. [Sidenote: Village Defense] The following was the actual scheme employed for the defense of a French village, and exemplifies the thoroughness with which defenses must be organized.