Air Evacuation of wounded solidiers began in WW2, this is the story of Jane Kendeigh, the first US-Navy Flight Nurse on Iwo Jima and Okinawa in 1945 while fighting was still going on:
US-Navy Flight Nurse, first on Iwo Jima and Okinawa 1945
US-Navy Flight Nurse, first on Iwo Jima and Okinawa 1945