quate communication within the bivouac; in de- fensive situations, wire communication may be es- tablished between subareas within the bivouac.
e. Security. (1) Security for the regimental train bivouac is provided by means of an area defense and a close-in defense. The division commander is responsible for the area defense of the entire divi- sion rear area. Close-in defense is the responsibility of the troops occupying the bivouac.
(2) The regimental commander is responsible for the security of all supply installations operating under his control. He usually charges the service company commander, under the general supervi- sion of the regimental S-4, with the close-in defense of the train bivouac. (See par. 50b(2) (b).) The S-4, assisted by the service company commander, prepares the plan for such defense and integrates it with the plan for area defense established by higher headquarters. Primarily, such plan will be based on the troops and weapons available within the bivouac but when the need for additional secu- rity is indicated, S-4 specifically recommends to the regimental commander the types and number of re- inforcements required. Upon approval of the plan by the regimental commander, the service company commander is charged with the detailed execution.
(3) When the trains of a battalion are bivouacked at a distance from the other trains of the regiment, the battalion S-4 provides for their security in the manner described above for the regimental S-4 and service company commander.