It was also realized that the field guns with which these mounts were to be equipped did not have the power and range that the war experience was showing to be necessary. The only reasons that the field guns of the 75-millimeter caliber were used in this way was because they were the guns most quickly available and because the French were already using them for this purpose.
To meet the need of more powerful antiaircraft weapons, a need becoming more pressing each day, a 3-inch high-powered antiaircraft gun was designed and mounted on a four-wheel trailer of the automobile type. This mount permitted elevations of the gun from 10 degrees to 85 degrees and also allowed for "all around" firing. An order for 612 of these carriages was given to the New Britain Machine Co. in July, 1917, shortly after the contract for the 51 truck mounts had been placed with that concern.
Because of the urgency of the situation it was necessary to construct these carriages without the preliminary tests on a pilot carriage. This, of course, is a very undesirable practice, but under the existing conditions no other procedure would have been practicable. The French antiaircraft auto truck mount, which had the French 75-millimeter field gun with its recuperator placed upon a special antiaircraft mount, was not adopted at the time, because, in July, 1917, the whole question of the possibility of constructing French recuperators in this country was still entirely unsettled. It was imperative then that we develop our own designs.
All of the 51 truck mounts for the antiaircraft guns were delivered during the fall and early winter of 1918, and 22 of them were in France before December, 1918.
Delivery of the first carriage for the 3-inch high-powered gun mounted on the trailer carriage was made in August, 1917. It had been rushed ahead of general production in order to be given some sort of a test. No further deliveries were made, but manufacture reached a point where production in quantity could begin.
A representative of the Ordnance Department was sent to France and England in December, 1917, to gather all the information possible on antiaircraft artillery. As a result of his investigations it was determined that it would be best to procure the greater part of our fire-control equipment in France, since the instruments developed there were in some cases of a highly complicated nature and their manufacture entirely controlled by private parties. Orders were placed for enough of these instruments for the equipment of the first 125 batteries.
Meanwhile, fire-control instruments of various types were in the process of development in this country; but, as they were largely based upon theoretical construction derived from study of the French practices, it was deemed best not to manufacture any of these instruments in quantity, as better instruments of French design were available. Drawings of the French instruments were brought back by the Ordnance officer on his visit to France and were available in this country in the spring of 1918, when manufacture of some of them began in the United States.
At the signing of the armistice our forces in France were equipped almost wholly with antiaircraft artillery loaned to us and supplied by the French. This, of course, does not include the 101 improvised and truck mounts completed during 1917. Production here, however, had reached such a point that shipment of material would have begun in quantity in January, 1919.
The estimated requirements of antiaircraft artillery for 2,000,000 men in 48 divisions is only 120 guns. Other material, of course, would have been required previously for defense of depots, railheads, etc., dependent in a great measure upon the activities of German bombers. It is estimated that about 200 guns would have sufficed for this purpose.
To summarize, 50 of the so-called improvised 75-millimeter antiaircraft guns and mounts had been ordered and completed up to the time of the signing of the armistice; 51 of the 75-millimeter antiaircraft mounts, model of 1917, had been ordered and 46 completed; while 612 of the 3-inch antiaircraft trailer carriage mounts, model of 1917, had been ordered, of which 1 had been actually delivered at the signing of the armistice, the balance to come at the rate of 26 per month starting in December.