I'm not going to retype the biography, you can read it here at the Jimmy Stewart Museum.
Here's what they say about his time in the service.
In the military, he was to make extensive use of his pilot’s training. In March 1941 at age 32, he reported for duty as Private James Stewart at Fort McArthur and was assigned to the Army Air Corps at Moffett Field. To comply with the regulations of the Air Corps proficiency board, Stewart required additional 100 flying hours and bought them at a nearby field, at this own expense. He then took and passed a very stiff proficiency board examination. In January 1942 Stewart was commissioned a 2nd Lieutenant. He was then sent to Mather Field in California as a twin engine instructor this included both the B-17 and B-24. Much to his dismay, Stewart stayed stateside for almost two years, until commanding officers finally yielded to his request to be sent overseas. In November 1943, now a Captain and Operations Officer for the 703rd Squadron, 445th Bombardment Group of the Eight Air Force, he arrived in Tibenham, England. In March of 1944 he was transferred to the 453rd Bombardment Group at Old Buckenham. While stateside, Stewart flew B-17’s (The Flying Fortress). In England he flew B-24’s (The Liberator) and did so for the remaining years of the war. Stewart’s war record included 20 dangerous combat missions as command pilot, wing commander or squadron commander. He was awarded the Distinguished Flying Cross with two Oak Leaf Clusters, The Air Medal with three Oak Leaf Clusters, and the French Croix de Guerre with Palm. At the end of the war he had risen to the rank of Colonel. After the war he remained with the US Air Force Reserves and was promoted to Brigadier General in 1959. His tuxedo and dress blues with all the correct medals are on display at The Jimmy Stewart Museum. He retired from the Air Force in 1968 (mandatory retirement age) and received the Distinguished Service Medal.You did go RTWT, right? Boy Scout, devoted husband and father, conservative in Hollywood, winner of all those award for humanitarian service? Performed in 80 movies over 55 years?
Here he is as a young man in a recruiting film for the Army Air Corps.
And here's some scenes from a few of his films with a narration by George Kennedy that gives a picture of Jimmy Stewart the actor.
And all that is good and interesting, but I'm going to give Jimmy Stewart himself the last word. He was being interviewed late in his life and was asked how he would like to be remembered.
I hope to be remembered as someone who believed in hard work and love of country, love of family and love of community.