Gotta reply to this one.
Helicopters were used operationally by the US during World War II as search and rescue aircraft over the "Hump". The first rescue by a USAAF helicopter happened April 25-26, 1944 in Burma.
The Museum of Aviation, near Robins Air Force Base in Macon Georgia, has a display with pictures of the helicopters in Burma. This same display gives information about their flights and usage. The main problem found with "choppers" was that the air was too thin for the machines to really operate. The technology was just too "new".
A "long distance" rescue can be read about
here.SIM