Lyndon Baines Johnson served in the US Navy Reserve during WW2 although he remained a Congressman. He flew as an observer on a bombing mission over New Guinea in 1942 and shortly after was a passenger on a B17 which force landed in north Queensland due to lack of fuel whilst returning from New Guinea.
Read more here
http://home.st.net.au/~dunn/tow9.htm
Cheers
Rod