In the production of these new devices there arose a new form of cooperation between Government and private manufacturers under the tutelage of the Trench Warfare Section. The manufacturers engaged in the production of various classes of these munition novelties joined in formal associations. There was a Hand Grenade Manufacturers' Association, under the capable leadership of William Sparks, president of the Sparks-Withington Co., of Jackson, Mich.; the Drop Bomb Manufacturers' Association, headed by J. L. Sinyard, president of A. O. Smith Corporation, Milwaukee; the Six-inch Trench-mortar Shell Manufacturers' Association, R. W. Millard, president of Foster-Merriam Co., Meriden, Conn.; the Rifle Grenade Manufacturers' Association, under the leadership of F. S. Briggs, president of the Briggs & Stratton Co., Milwaukee, Wis.; and the Livens Projector Manufacturers' Association. A similar association of manufacturers engaged in army contracts existed in the production of small-arms ammunition; but in no other branch of the Ordnance Department was the development of such cooperation carried on to the extent of that fathered by the Trench Warfare Section. The existence of these associations was of inestimable benefit in securing the rapid development, standardization for quantity manufacture, and production of these strange devices. Each association had its president, its other officers, and its regular meetings. These meetings were attended by the interested officers of the Trench Warfare Section. In the meetings the experiments of the manufacturers and the short-cut methods developed in their shops were freely discussed; and, if modifications of design were suggested, such questions were thrashed out in these meetings of practical technicians, and all of the contractors simultaneously received the benefits. The Trench Warfare Section produced its results under the handicap of being low in the priority ratings, many other items of ordnance being considered in Washington of more importance than the trench-fighting materials and therefore entitled to first call upon raw materials and transportation. In the priority lists the leader of 47 trench-warfare articles, the 240-millimeter mortars, stood twenty-second, and the others trailed after. GRENADES. The first of the trench-warfare weapons with which the rookie soldier became acquainted was the hand grenade, since this, at least in its practice or dummy form, was supplied to the training camps in this country. To all intents and purposes the hand grenade was a product of the war against Germany, although grenades had been more or less used since explosives existed. All earlier grenades had been crude devices with only limited employment in warfare, but in the three years preceding America's participation in the war the grenade had become a carefully built weapon.