A third development was known as the gas grenade. It was built of sheet metal, and its toxic contents were effective in making enemy trenches and dugouts uninhabitable. A fourth, a grenade of similar construction, was filled with phosphorus, instead of gas, and was known as the phosphorus grenade. This grenade scattered burning phosphorus over an area 3 to 5 yards in diameter and released a dense cloud of white smoke. In open attacks upon machine-gun nests phosphorus grenades were thrown in barrages to build smoke screens for the attacking forces.
As a fifth class there was a combination hand and rifle grenade, a British device adopted in our program. The sixth class of grenades was known as the incendiary type. These were paper bombs filled with burning material and designed for use against structures intended to be destroyed by fire. Finally, in the seventh class were the thermit grenades, built of terneplate and filled with a compound containing thermit, which develops an intense heat while melting. Thermit grenades were used principally to destroy captured guns. One of them touched off in the breech of a cannon would fuse the breech-block mechanism and destroy the usefulness of the weapon.
All of these grenades except the incendiary grenades used the same firing mechanism, and the incendiary grenade firing mechanism was the standard one modified in a single particular.
The earliest American requirement in this production was for defensive grenades, of the fragmentation type. Our first estimate was that we would need 21,000,000 of these for actual warfare and 2,000,000 of the unloaded type for practice and training work. But, as the war continued and the American plans developed in scale, we saw we would require a much greater quantity than this; and orders were finally placed for a total of 68,000,000 live grenades and over 3,000,000 of the practice variety.
By August 20, 1917, the Trench Warfare Section had developed the design and the drawings for the defensive grenade. The first contract—for 5,000 grenades—was let to the Caskey-Dupree Co. of Marietta, Ohio. This concern was fairly entitled to such preference, because the experimentation leading up to the design for this bomb was conducted almost entirely at its plant in Marietta.
Next came an interesting industrial development by a well-known American concern which had previously devoted its exclusive energy to the production of high-grade silverware, but which now, as a patriotic duty, undertook to build the deadly defensive grenades. This was the Gorham Manufacturing Co. of Providence, R. I. This firm contracted to furnish complete, loaded grenades, ready for shipment overseas, and was the only one to build and operate a manufacturing and loading plant. Elsewhere contracts were let for parts only, these parts to converge at the assembling plants later; and such orders were rapidly placed until by the middle of December, 1917, various industrial concerns were tooling up for a total production of 21,000,000 of these missiles.
The grenade which these contractors undertook to produce was an American product in its design, although modeled after grenades already in use at the front. Its chief difference was in the firing mechanism, where improvements, or what were then thought to be improvements, had been installed to make it safer in the hands of the soldier than the grenades then in use at the front. This firing mechanism with its pivoted lever was, in fact, a radical departure from European practice. The body of this grenade was of malleable iron, and the grenade exploded with a force greater than that of any in use in France.
The remodeling of factories, the building of machines, and the manufacture of tools for this undertaking, pushed forward with determined speed, was completed in from 90 to 120 days, and by April almost all of the companies had reached the stage of quantity production.
And then, on May 9, 1918, came a cablegram from the American Expeditionary Forces that brought the entire effort to an abrupt halt. The officers of the American Expeditionary Forces in no uncertain terms condemned the American defensive grenade. The trouble was that in our anxiety to protect the American soldier we had designed a grenade that was too safe. The firing mechanism was too complicated. In the operation required to touch off the fuse five movements were necessary on the part of the soldier, and in this the psychology of a man in battle had not been taken sufficiently into consideration. The well-known story of the negro soldier who, in practice, threw his grenade too soon because he could feel it "swelling" in his hand, applies to most soldiers in battle. In using the new grenade the American soldier would not go through the operations required to fire its fuse. Cases came to light, too, showing that in the excitement of battle the American soldier forgot to release the safety device, thus giving the German an opportunity to hurl back the unexploded grenade.
As the result of this discovery all production was stopped in the United States and the ordnance engineers began redesigning the weapon. The incident meant that 15,000,000 rough castings of grenade bodies, 3,500,000 assembled but empty grenades and 1,000,000 loaded grenades had to be salvaged, and that on July 1, 1918, the production of live fragmentation grenades in this country was represented by the figure zero. Some of the machinery used in the production of the faulty grenades was useless and had to be replaced by new, while the trained forces which had reached quantity production in April had to be disbanded or transferred to other work while the design was being changed.