The A.D.S. is usually situated a mile or so in the rear of the trenches, preferably in a large cellar, but at any rate in a fairly well sheltered area where cots are ready to receive fifty or more patients. At the A.D.S. one or two of the medical officers of the field ambulance are stationed with a large staff of men. The patient is here made comfortable; given coffee or cocoa; name, number and battalion recorded; and finally he is inoculated with anti-tetanic serum. This has practically wiped out tetanus, or lock-jaw, which was very prevalent at the beginning of the war. He is kept here till a convenient time, which may be after dark, when he and any others who may have come in are put into ambulances and taken to the M.D.S.--main dressing station--of the field ambulance, another two or three miles behind. The M.D.S. may be in some old château, or in a group of huts, or, if the weather is mild, in tents. Here a light case, or slightly wounded man, may be kept for a few days and then sent back to the line or to a rest station to recover his stamina and quiet his nerves. But if the case should be a serious one, such as a shattered leg or arm or a large flesh wound that will take a considerable time to heal, he is again transferred by ambulance to the C.C.S.--Casualty Clearing Station--another two to four miles back. The C.C.S., usually in huts or tents, is the first real hospital behind the firing zone. It may have accommodation for a couple of hundred patients; is supplied with X-Ray equipment, a well-arranged operating room with expert surgical assistance, and is the nearest place to the line that trained nurses are sent. Here for the first time since he left the line the patient gets all those little motherly attentions that only a woman can give. The injured man may be kept here days, weeks, or even months if he happens to be a case that would be endangered by moving. All immediately necessary operations are at once performed, and often a seriously wounded man from the firing line may be lying anesthetized on the operating table of a C.C.S., being operated upon by expert surgeons within two or three hours of receiving his injury--practically as good attention as this type of injury would receive in civil life.