I was curious, so I checked Wikipedia:
America's entry into
World War II resulted in a deluge of support for the war effort from all sectors of society, and Hollywood was no exception. Wayne was exempted from service due to his age, although actor Henry Fonda born two years earlier volunteered and served three years, (34 at the time of
Pearl Harbor) and family status, classified as 3-A (family deferment). He repeatedly wrote to John Ford saying he wanted to enlist, on one occasion inquiring whether he could get into Ford's military unit, but consistently kept postponing it until after "he finished just one or two pictures". Wayne did not attempt to prevent his reclassification as 1-A (draft eligible), but
Republic Studios was emphatically resistant to losing him.
Herbert J. Yates, President of Republic, threatened Wayne with a lawsuit if he walked away from his contract, and Republic Pictures intervened in the Selective Service process, requesting Wayne's further deferment.
Wayne toured U.S. bases and hospitals in the South Pacific for three months in 1943 and 1944. with the
USO. By many accounts, his failure to serve in the military was the most painful part of his life. His widow later suggested that his patriotism in later decades sprang from guilt, writing: "He would become a 'superpatriot' for the rest of his life trying to atone for staying home."
U.S. National Archives records indicate that Wayne had, in fact, made an application to serve in the
Office of Strategic Services (OSS), that day's equivalent of the
CIA, and had been accepted within the U.S. Army's allotted billet to the OSS.
William J. Donovan, OSS Commander, wrote Wayne a letter informing him of his acceptance into the Field Photographic Unit, but the letter went to his estranged wife Josephine's home. She never told him about it. Donovan also issued an OSS Certificate of Service to Wayne.
I had heard that he had a deferment , but that he did do volunteer work for the war effort. Now you know more.