It was often difficult to believe that this quiet backwater was within an hour or two of the trenches. G.H.Q. was indeed situated well back behind "the Front," which, however precise the maps in the newspapers may affect to make it, is, like the Equator of our school-books, a more or less "imaginary line drawn across the earth's surface." Imaginary because if a line be, as we were taught with painful reiteration, length without breadth, then "the Front" is not a line at all, much less a straight line in the sense of the shortest distance between two points. It is not straight, for it curves and sags and has its salients and re-entrant angles; and it is not a line, for it has breadth as well as length. Broadly speaking, the Front extends back to the H.Q. of the armies (to say nothing of the H.Q. of corps, divisions, and brigades), and thence to G.H.Q. itself, which may be regarded as being "the Back of the Front," to vary a classical expression of _Punch_. The Front is, indeed, to be visualised not as a straight line but as a fully opened fan, the periphery of which is the fire-trenches, the ribs the lines of communication, and the knob or knuckle is General Headquarters. When we extend our Front southwards and take over the French trenches we just expand our fan a little more. When we come to make a general advance all along the periphery, the whole fan will be thrust forward, and the knuckle with it, for the relative distances of General Headquarters, and minor Headquarters, from this periphery and from one another are a more or less constant quantity, being determined by such fixed considerations as the range of modern guns and the mobility of transport. From G.H.Q., the brain of the Army, the volitional centre of the whole organism, radiate the sensory and motor nerves by which impressions at the Front are registered and plans for action transmitted. It is the home of the Staff, not of the Armies, and contains more "brass hats" than all the other Headquarters put together. Beyond the "details" in the barracks it contains few of the rank and file, and its big square betrays little of the crowded animation of the towns nearer the fighting line, with their great parks of armoured cars, motor lorries, and ammunition waggons, their filter-carts, and their little clusters and eddies of men resting in billets. The Military Police on point-duty have a comparatively quiet time, although despatch-riders are, of course, for ever whizzing to and fro with messages from and to the Front. It is as full of departmental offices as Whitehall itself--some 153 of them to be exact--each one indicated by a combination of initial letters, for staff officers are men of few words and cogent, and it saves time to say "O." when you mean Operations, "I." for Intelligence, "A.G." for Adjutant-General; a fashion which is faithfully followed at the other H.Q., for D.A.A.Q.M.G. saves an enormous number of polysyllables.