During World War I, General John J. Pershing ordered the creation of a separate organization within the Military Police Corps to prevent and detect crime among the American Expeditionary Force in France. The newly created Criminal Investigation Division (CID) was headed by a division chief who served as the advisor to the Provost Marshal General on all matters relating to criminal investigations. However, operational control of CID still remained with individual provost marshals, and there was no central control of investigative efforts within the organization, resulting in limitations. At the end of the war, the United States Army was reduced in size during the transition to peacetime and the size of CID shrank dramatically.