The extent of our production of hand grenades may be seen in the fact that when the effort was at its height 10,000 workers were engaged exclusively in its manufacture. The firing mechanism of the explosive grenades which we built was known as the Bouchon assembly. In the production of this item 19 of every 20 workers were women. In fact no other item in the entire ordnance field was produced so exclusively by women. Incidentally, at no time during the war was there a strike in any grenade factory. For a long time in the trenches of France only one type of hand grenade was used. This was the so-called defensive grenade, built of stout metal which would fly into fragments when the interior charge exploded. As might be expected, such a weapon was used only by men actually within the trenches, the walls of which protected the throwers from the flying fragments. But, as the war continued, six other distinct kinds of grenades were developed, America herself contributing one of the most important of them; and during our war activities we were engaged in manufacturing all seven. The defensive, or fragmentation, type grenade was the commonest, most numerous, and perhaps, the most useful of all of them. Another important one, however, was that known as the offensive grenade, and it was America's own contribution to trench warfare. The body of the offensive grenade was made of paper, so that the deadly effect of it was produced by the flame and concussion of the explosion itself. It was quite sure to kill any man within 3 yards of it when it went off, but it was safe to use in the open offensive movements, since there were no pieces of metal to fly back and hit the thrower. 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.