There was no need for the Ordnance Department during the demobilization to exercise so much care looking to the future production of artillery carriages, and for the reason mentioned, that the manufacture of carriages was easier than the manufacture of guns and recuperators. Carriages can be produced with machinery essentially the same as that used in making motor trucks, street cars, and other heavy vehicles. Consequently, the War Department contented itself with reserving enough machinery to equip at Rock Island Arsenal a model carriage-building department large enough to maintain the existing reserves of artillery and to experiment with new designs. This plant can now manufacture every month one hundred carriages for the lighter field artillery--for the 75’s, the 4.7’s, and the 155’s, both howitzers and guns. In addition, at Rock Island have been concentrated jigs, fixtures, gauges, and special tools used by the war factories, this equipment being boxed, catalogued, and ready for instant shipment to commercial factories that may be called upon to build artillery carriages in a hurry. No machine tools used in carriage building, however, have been retained. The same economic, military, and business reasons that influenced the post-armistice production of guns and recuperators, controlled also the closing down of the carriage plants. There was a considerable production of field artillery carriages after the immediate military need for them had passed. The artillery war orders called for the production of about 20,000 complete units, a unit being a gun, recuperator, carriage, and accompanying limbers and caissons. The total production attributable to the war was 6,663 complete units, produced about half before the armistice and half afterwards. The value of this _matériel_, together with the semi-finished components retained, was about $300,000,000. After the armistice the General Staff adopted the policy that in the demobilization sufficient mobile field artillery should be retained to equip an army of twenty divisions--800,000 men--with reserves to take care of battle wastage over a period of six months, during which interval a new artillery industry would be brought into existence. It is interesting to note how completely the Ordnance Department met this policy. Including the 6,000 field guns brought back by the American Expeditionary Forces (this figure not including captured _matériel_), the Army now has an equipment of about 10,000 artillery units.[7] The staff plan indicates 2,583 as the proper number of 75-millimeter guns to be in reserve: the Army actually possesses 6,000. The projected army of twenty divisions needs 986 155-millimeter howitzers: the War Department owns 2,171. The projected force should have 976 155-millimeter guns: the Army to-day owns 993. These liberal margins obtain throughout the range of mobile field guns.