In the five and six-inch guns that could despaired from the Coast Artillery and the reserve store of the Navy there was shell power that might quickly be made available for the western front. When the United States entered the war the Ordnance Department at once set out to master the problem of placing these heavy fixed emplacement pieces on mobile field Mounts.

An inventory showed that ninety-five six-inch and twenty-eight 5-inch guns could be secured from the Coast Artillery and forty-six 6-inch guns from the Navy, while an additional 30 guns of the six-inch size were offered by a private dealer in this country. Minor alterations were necessary in many of the guns to make them adaptable to field mounts, and the Navy guns, ranging from 30 to 50 calibers in length, had to be cut down to a uniform length of 30 calibers. The long six-inch seacoast guns were not shortened because it was planned to return them to the Coast Defenses from which they were taken.

Speed in the manufacture of the Carriages for these Guns demanded that they be of the simplest design consistent with the great strength necessary to bear the weight of this fixed emplacement material. The carriage designed for the five and six-inch naval guns having been placed under test and found to meet all requirements by September of 1917 and orders were placed for ninety-two 6-inch Carriages and twenty-eight five-inch Carriages. Owing to the great weight of the long six-inch seacoast guns, however it was found at that it would be necessary to carry them separately on big transport wagons. Such a wagon was designed and an order placed for 55 wagons in February of 1918.

When the Armistice was signed practically all of these mounts had been completed. Seventy-two entirely assembled six-inch units and twenty-six; five-inch units had been shipped for overseas duty.