The nations engaged in the war now ending developed to a high stage the use of heavy artillery mounted on railway cars, bringing about a combination of the necessary rigidity with great mobility, considering the weight of this material. Railway artillery came to be as varied in its design as field artillery. Each type of railway mount had certain tactical uses and it was not considered desirable to use the different types interchangeably. The three types of cannon used on railway mounts were mortars, howitzers, and guns. It was not practicable to use the same type of railway mounts for the different kinds of cannon. Moreover, these mounts differed radically from the mounts for such weapons at the seacoast defenses. The three general types of railway mounts adopted were those which gave the gun all-around fire (360-degree traverse), those which provided limited traverse for the gun, and those which allowed no lateral movement for the gun on the carriage but were used on curved track, or epis, to give the weapons traverse aim. The smaller weapons, such as the 7-inch and the 8-inch guns and the 12-inch mortars, were placed on mounts affording 360-degree traverse. The limited traverse mounts were used for the moderately long-range guns and howitzers. The fixed type of mount was used for long-range guns only, and included the sliding railway mounts, such as the American 12-inch and 14-inch sliding mounts and the French Schneider à glissement mounts. The work of providing railway artillery--that is, taking the big, fixed-position guns already in existence within the United States and similar guns being produced and designing and manufacturing suitable mounts for them on railway cars--grew into such an important undertaking that it enlisted the exclusive attention of a large section within the Ordnance Department. This organization eventually found itself engaged in 10 major construction projects, which, in time, had the war continued, would have delivered more than 300 of these monster weapons to the field in France and, to a lesser extent, to the railway coast defenses of the United States. As it was, so much of the construction--the machining of parts, and so on--was complete at the date of the armistice, that it was decided to go ahead with all of the projects except three, these involving the mounting of 16 guns of 14-inch size, 50 calibers long, the production of 25 long-range 8-inch guns, 50 calibers, and their mounting on railway cars, and the mounting of 18 coast-defense, 10-inch guns, 34 calibers long, on the French Batignolles type of railway mount. Inasmuch as it will be necessary in this chapter to refer frequently to the barbette, Schneider, and Batignolles types of gun mounts for railway artillery, it should be made clear to the reader what these types are.