The method of caring for the wounded at the front depends a great deal upon whether a battalion is holding a set of trenches on a standing front, or advancing, either in a big push, or in a raid. The medical officer to a fighting battalion is the member of the Army Medical Corps who is closer to the firing line than any of the other officers of that corps in the whole theater of war. He is served by the nearest field ambulance, whose stretcher bearers not only evacuate the wounded from his R.A.P.--regimental aid post--but also keep him supplied with medicines, dressings, splints, and other medical and surgical necessities. His food is sent up with that of the remainder of his battalion from his own battalion transport. The field ambulance evacuates the severe cases to the nearest C.C.S.--casualty clearing station--which is the closest hospital to the lines. It is at the C.C.S. that the necessary operations are performed. Here the real surgical work of the medical corps begins, for up to that station it is much a matter of first aid. From the casualty clearing station cases that look as if they will require protracted attention are transferred to ambulance trains, which convey the cases fifty, sixty, or more miles to the base hospitals at the rear, perhaps about Boulogne, Havre and other towns reasonably well out of danger. And from these hospitals the wounded or sick may be transferred again, this time to hospital ships which cross the channel to one of our channel ports. At these points they are once more put aboard ambulance trains and distributed to hospitals in London, Manchester, Canterbury, Edinburgh or any of the other large hospital centers. Suppose that a battalion is holding a part of the entrenched front, roughly one thousand yards square. The medical officer always travels with his battalion. In an area such as this his R.A.P. would be in a dugout somewhere in the vicinity of the one which is used as headquarters for the battalion. A medical officer's position is toward the rear of his battalion whether the men are on the march, in an advance, or holding the lines, for the reason that the wounded and sick are naturally sent toward the rear. Very commonly the R.A.P. is about half way from the rear support trench to the firing line.