One of the major combat support chores is getting wounded troops back to a field hospital. The speed with which this is done spells the difference between life and death. Basically, the longer it takes to get a wounded soldier to a field hospital, where extensive care can be provided, the more likely the wounded man will die. Get the transit time to under an hour, and only a few percent of the wounded will die. A century ago, and through World War I (1914-18), it typically took 15 hours to get a wounded soldier to a field hospital. During World War II (1939-45), this was reduced to nine hours, largely because there were more trucks and jeeps available. But at the end of World War II, the helicopter showed up, and prominent among its first missions was getting wounded soldiers back to hospitals. So by the time the Korean War (1950-53) came along, evacuation only took three hours. Vietnam (1965-70) saw extensive use of helicopters, and the average time to reach a hospital was half an hour. This time hasn't changed much, and has actually gone up a bit in Afghanistan because of the longer distances covered, and fewer casualties encountered. More effective medical care onboard the helicopter has also raised survival rates.