WHEN HIPPOCRATES wrote in the fifth century B.C. that “he who would learn surgery should join an army and follow it,” he illuminated the central irony of military medicine. Destructive as war is, it makes possible quantum leaps in the art of healing. And it is the surgeon who benefits most directly: war has been described as an “epidemic of trauma,” and the vast supply of wounded men provides opportunities for experimentation and innovation unthinkable in a world at peace. But surgery is not the only branch of medicine that advances. In all wars fought before World War I, more men died from disease than from military action, so the necessity of keeping troops on the field provides a powerful impetus to wipe out the illnesses that prey on armies. Finally, there is the matter of logistics—how to move a man quickly to a place where he can be treated. Here, too, lessons learned in wartime have dramatically improved health care when peace came.

The six pictures that follow reveal much about medical care in America’s major wars since the beginning of photography. The Civil War was the last great conflict waged before germ theory entered medicine. Hospitals were unsanitary places, where, as the surgeon W. W. Keen later described it: “We operated in old blood-stained and often pus-stained coats, the veterans of a hundred fights. We operated with clean hands in the social sense, but they were undisinfected hands. … We used undisinfected instruments from undisinfected plush-lined cases. … If a sponge or instrument fell on the floor it was washed and squeezed in a basin of tap water and used as if it were clean. ” The troops were plagued by malaria, diarrhea, dysentery, typhoid, and respiratory diseases. In the first years of the war, ambulances were in short supply, and the civilians hired to drive them fled at the first sounds of shooting. Three days after the second battle of Bull Run, some three thousand wounded men still lay on the field, and Washington hospitals were so overcrowded that cots were set up in the halls of Congress. Like thousands of others, Oliver Wendell Holmes traveled to the front three times to take his son home for treatment rather than leave him to the uncertainties of military medicine.

Two years after the Civil War ended, the British surgeon Joseph Lister published his work on antisepsis, laying the groundwork for accelerated progress in the Spanish-American War, the two World Wars, and Korea. But impressive as its past has been, the future of military medicine is less certain. In Vietnam the advances were primarily in logistics, not medicine. And as the nation’s doctors have tried to make clear, if there is all-out nuclear war, they will be powerless to help.

—Jane Colihan

THE CIVIL WAR: cutting and sawing THE SPANISH-AMERICAN WAR: conquering yellow fever WORLD WAR I: tetanus and plastic surgery