During the Civil War, soldiers feared bullets and bayonets on the battlefield, but the greater danger in both Union and Confederate camps was communicable disease spread by poor hygiene and little understanding of public health. By 1865, 620,000 men were casualties of war, and the bulk died from diseases such as pneumonia, tuberculosis, and dysentery, including three out of every five Union soldiers and two out of every three Confederate soldiers. Inspection records of Federal camps in 1861 found men living amid refuse, food, rubbish, slops, manure, and offal in offensive conditions that helped illness spread, and at Darnestown the 27th Indiana regiment lost 15 men to measles and typhoid. Hospitals for wounded soldiers operated in tents, in the backs of ambulance wagons, in existing buildings, and in newly built permanent structures such as Carver Hospital on Meridian Hill in Washington D.C. At the start of the war, the medical profession was unprepared and did not understand how infection spread through unclean hands and unsterilized equipment, a condition Union Surgeon General William Hammond called fighting at the end of the Medical Middle Ages. By the war’s close, medicine had advanced through the use of anesthesia during surgery, better record keeping, and a larger role for women in nursing. Clara Barton became the best-known female nurse of the war, and her combat experience led her to found the American Red Cross in 1881; her home in Glen Echo later served as its headquarters from 1897 to 1904, and since 1975 the National Park Service has operated it as a National Historic Site in Montgomery County.