In any case, the details of construction, equipment and operation of a military railway vary from those of a commercial railway since the one would be intended to serve only a specific and possibly temporary purpose, in the attainment of which the question of speed would be a secondary consideration, whereas the other would require to assume a permanent form, be capable of higher speeds, and afford adequate guarantee of safety for the public, by whom it would be used. The building, also, of a military railway may be, and generally is, carried out by a corps of Railway Troops to which are specially delegated the duties of laying, working, maintaining, repairing, restoring or destroying railways; and, provided the desired lines were built with sufficient dispatch, and answered the desired purpose, the military commanders who would alone be concerned might well be satisfied. In many different ways the resort to military railways, whatever their particular type, has greatly extended the range of advantages to be gained from the application of rail-power to war. A full record of all that has been accomplished in this direction could hardly be attempted here; but a few typical examples of what has been done in this direction--though not always with conspicuous success--may be offered. THE CRIMEAN WAR The earliest instance of a purely military railway being constructed to serve the purpose of a campaign occurred in the Crimean War; and, although the line then made would to-day be regarded as little more than an especially inefficient apology for a railway, it was looked upon at the time as a remarkable innovation in warfare. It further established a precedent destined to be widely followed in later years.