Introduction

 Casualties on the battlefield are moved to medical care one by one. Within the battle area, the combat zone, patients are moved individually, or a few at a time. True, a field hospital might have to deal with 10 or 20 at a time, or even more. The focus is still on the individual soldier who is injured. But back in the rear area, in what is now called the communications zone, casualties begin to take on an aspect of mass movement. A major battle might generate several thousand casualties within a division, tens of thousands within an entire army. Over a campaign, hundreds of thousands of men will have to be moved from collecting areas near the front lines back to specialty hospitals and hospital centers capable of dealing with patients arriving literally by the trainload. The American Expeditionary Force sustained 200,000 casualties during the six to eight months in which it saw heavy combat. How was it organized to transport and care for 20,000 to 40,000 patients each month?