On 1 February 1943, Camp Ellis was activated and designated the Armies seconed ASF (Army Service Forces) unit training center. Initially, the post served as a center for training units of the Quartermaster Corps, the Corps of Engineers, the Signal Corps, and the Medical Department. After the preactivation system was established, Camp Ellis also served briefly as a replacement training center. Under the new program, medical trainees assigned to Ellis were assigned to the 30th, 31st, and 32d Medical Training Regiments for 6 weeks of basic military training under ASF programs at facilities controlled by the post commander. After completing this phase, they were transferred to the 28th and 29th Medical Training Regiments for technical and tactical training under Medical Department programs.. At first, the center attempted to operate under a common headquarters, but within a short time, it was realized that the special training requirements of each of the technical services made this structure too cumbersome.
After several reorganizations, the medical section was established as a separate entity early in May 1943. On 10 November 1944, the 28th Medical Training Regiment was disbanded, followed on 16 December by the 29th. From February 1943 to January of 1945, the two units were each able to complete many 8-week training cycles, and a total of 15,531 men were trained.
20 Hospital Units would in fact be activated at Camp Ellis on May 25, 1943 – 8 Station Hospitals, 3 Ambulance Companies, 2 General Hospitals, 2 Medical Sanitary Companies, 1 Field Hospital, 1 Medical Gas Treatment Battalion, 1 Medical Ambulance Battalion, 1 Convalescent Hospital, and 1 Headquarters Medical Service. In June another 12 medical units followed, while additional ones were being organized and started training. In December of 1943, 79 medical units were prepared for training, including Malaria Survey Units, Malaria Control Units, Hospital Trains, and General Dispensaries. Camp Ellis closed its doors February 1, 1945, having helped activate and train a total of 266 medical units!
The medical section at Camp Ellis played a primary role in the training of medical units. It operated a school for cooks, bakers, truckdrivers, and other common specialists, and, in addition, conducted courses for unrated medical, surgical, X-ray, dental, and pharmacy technicians. A weeklong orientation course was provided for the unit commander, his adjutant, executive officer, and supply officer, to acquaint them with the problems of unit activation. The medical section also assisted the various units at Camp Ellis to secure training aids and provided them with general, station, and field hospital equipment sets for use on field problems.
| 6th Medical Center | ||
| 7th Convalescent Hospital | 280th Station Hospital | |
| 37th Field Hospital | ||
| 39th Field Hospital | ||
| 47th Field Hospital | 116th General Hospital | |
| 67th Field Hospital | ||
| 86th Field Hospital October 1944 | ||
| 52nd Portable Surgical Hospital | 121st General Hospital | |
| 123rd General Hospital | ||
| 54th Portable Surgical Hospital Became 914th Mobile Army Surgical Hospital | 199th General Hospital | |
| 202nd Malaria Survey Detachment | ||
| 58th Portable Surgical Hospital | 759th Medical Sanitary Company | |
| 72nd Malaria Control Unit | 914th Mobile Army Surgical Hospital was the 54th Portable Surgical Hospital | |
| 82nd Medical Company | ||
| 85th Malaria Control Unit | ||
| 85th Malaria Survey Unit | ||
| 85th Medical Detachment | ||
| 92nd Field Hospital | ||
| 92nd Field Hospital Activated 30 October 1944 at Camp Ellis, Illinois (off site) |