In years past the Ordnance Department had procured a large number of 12-inch mortars for use at seacoast defenses. These great weapons are 10 calibers in length, or 10 feet in linear measurement, the diameter of the barrel being just an even foot. Of the number stationed at the coastal forts and in reserve it was decided that 150 could be safely withdrawn and prepared for use against Germany. When Gen. Pershing was informed of the proposal, he asked that 40 of these weapons mounted on railway cars should be delivered to the American Expeditionary Forces for use in the planned campaign of 1919. In order that there might be an adequate supply of them, the Ordnance Department let contracts for the mounting of 91 of these mortars on railway equipment, a project which would give the United States a formidable armament and still provide a reserve of 59 mortars to replace the service mortars on the carriages after repeated firing had worn them out. This job proved to be one of the largest in the whole artillery program. The entire contract was let to the Morgan Engineering Co., of Alliance, Ohio. In order to handle the contract, a special ordnance plant, costing $1,700,000 for the building alone, had to be constructed at the company's works at Alliance. The work was so highly specialized that machine tools designed for the particular purpose had to be produced. The Government itself bought these tools at a cost of $1,800,000. Although work on this plant was not started until December 10, 1917, and although thereafter followed weeks and weeks of the severest winter weather known in recent years, with all the delays in the deliveries of materials which such weather conditions bring about, the plant was entirely complete on June 1, 1918, not only, but the work of producing the mounts had started in it long before that, some machines getting to work as early as April. The gun car used for mounting the mortar carriage was of the same design as that for the 7-inch and 8-inch guns, except that each truck had six wheels. The carriage built upon this car was of the barbette type, and it allowed the gun to be pointed upward to an angle as high as 65° and provided complete traverse, so that the mortar could be fired in any direction from the car. A hydropneumatic system for absorbing the recoil of the mortar after firing was adopted. This recuperator in itself was a difficult problem for the manufacturer to solve, being the first hydropneumatic recuperator of the size ever built in this country. [Illustration: 12-INCH SEACOAST GUN ON A CREUSOT RAILWAY MOUNT. This huge weapon in this position is ready to fire half a ton of shot a distance of 25 miles. It requires only two men to operate the powerful elevating apparatus necessary to bring the gun into quick-firing position.] [Illustration: TWO VIEWS OF 12-INCH MORTAR ON RAILWAY MOUNT. Lower view shows the mortar in its extreme position of recoil.]