The principal means of communication are the telephone, telegraph, wireless, aeroplane, mounted messengers, autos and motorcycles; and at the front runners, visual signals, rockets and carrier pigeons. Each battalion commander is connected by telephone with each company commander, with the artillery observers, with the artillery commander, with his own colonel and with the adjacent battalions on either side. The signallers of assaulting companies move with the company commander. All signallers should be given a special training in repeating a message several times to a known back station which may not be able to reply forward. At the commencement of the assault the pigeons and pigeon carriers must be kept back at battalion headquarters, and sent forward as soon as the position has been gained. Runners can be relied upon when all other means fail. They must be trained with their companies. Runners should be lightly equipped and wear a distinctive mark. They must be familiar with all the principal routes to all the principal centers within their battalion sector. The quicker they go the safer they are. Company and platoon runners must go forward with their respective commanders. Messages to be carried long distances will be relayed. Never send a verbal message by a runner; ignore any received; all messages must be written. Company and battalion commanders must be prepared to assist artillery liaison officers in getting their messages back. Liaison officers must be exchanged by all the assaulting battalions with the battalion on either flank. Trench Orders.--(Battalion): Trenches are usually divided into a certain number of bays; the number of men to defend these bays depends upon the length of trench allotted to each company. Each section is detailed to guard a certain number of bays. Non-commissioned officers and men must always wear their equipment by day and night. Every company will "Stand To" arms daily one-half hour before dusk and one-half hour before dawn, and will remain until dismissed by the company commander. The enemy's trenches are so close that it is very important for the men to have their rifle sights always at battle sight, so that there will be no necessity to alter their sights in case of alarm. By night all bayonets are to be fixed and half of the men on duty in the trenches are to be sitting on the firing platform with their rifles by their side. In case of attack, especially at night, it should be impressed upon the men that they fire low. Section commanders are responsible that the men under their command have sufficient standing room for the purpose of firing over the parapet. They must have a clear field of fire, and not only be able to see the enemy trenches but the ground in the immediate vicinity of their trench. When making new trenches parapets should be at least five feet thick at the top in order to be bullet proof.