2. To act on the flank of a column or line of columns, the train being well advanced so as to prevent the enemy breaking to that flank. 3. To reinforce stations and camps on the railway which were threatened by the enemy. 4. To escort ordinary traffic trains. 5. To reconnoitre. 6. To patrol by day and night. 7. To protect traffic routes generally. The garrison of an armoured train consisted of an Infantry escort and Royal Artillery and Royal Engineer detachments. The R.E. detachment consisted of one N.C.O. and six sappers skilled in railway repairing work and in re-setting derailed engines and trucks; two telegraph linesmen; one telegraph clerk; two engine-drivers and two firemen. When the train was engaged, all counted as effective rifles with the exception of the driver and firemen on the footplate, and even they carried rifles in their engine cab for use against an enemy endeavouring to gain possession of the engine. Responsibility for the efficiency of the garrisons was placed upon the Assistant-Director of Armoured Trains. Whenever, also, a concentration of the trains had been decided upon, he was to attach himself to one of them, and take charge of the concerted action of the whole. In reference to the operation of the trains Captain M. H. Grant writes[45]:-- It was important that the officer commanding the train should be a man of judgment and strong nerve. He was often called upon to act on his own responsibility. His strong armament and defences enabled him to attack superior forces. Yet his vulnerable points were many. He had ever to be alert that the enemy did not cut the line behind him. In addition to his visible foes and the constant risks of traffic in war time, he had to contend with skilfully-used automatic and observation mines, and had to keep his head even amid the roar which followed the passage of his leading truck over a charge of dynamite, and then to deal with the attack which almost certainly ensued. Officers, therefore, had to be chosen from men of no common stamp. The danger from contact mines was to a certain extent obviated by a standing order that each train should propel a heavily-loaded bogie truck. Such trucks had low sides and ends; they in no way obstructed the view, or fire, from the trains; and they performed the double purpose of exploding contact mines and carrying the railway and telegraph materials. The necessity for this propelled unoccupied bogie was exemplified on several occasions.