Major General William L. Sibert was the first Chief of the Chemical Warfare Service (CWS) from 1918 until 1920. In June of 1918, he brought his extensive experience in organizing and conducting complex engineering projects to bear on the chaotic American effort in gas warfare.

He consolidated the work of the Medical, Ordnance, Signal and Engineer Corps and the U.S. Bureau of Mines into one agency. The result, the CWS, had an authorized strength of 4,060 officers and 44,615 enlisted men.

Major General Sibert directed the total American effort in research and development in chemical munitions and in the standardization of doctrine, materiel, and training. His effort welded together the great U.S. Chemical Warfare Machine, ensured unity of effort, and brought the CWS to maturity as a permanent, separate branch of the United States Army.