• Studio Pressure: As the primary A-list star for Republic Pictures, studio executives aggressively lobbied to keep him out of the draft. The studio threatened a lawsuit if he walked away from his contract to enlist.
• Occupational Deferment: His classification was later changed to a 2-A occupational deferment because studio heads argued his morale-boosting films served the national interest.

The version I read was he colluded with the studio honchos, until he aged out of the draft.

Stewart was also a major star. He enlisted. He was originally rejected as underweight, so he went on a weight gain regime to be accepted. He was initially kept in the US, as an instructor, for a year. He was finally allowed to go the England and join a combat unit, at his request. He flew 20 combat missions. I have read that, when making "It's A Wonderful Life", right after the war, he did the breakdown scenes by letting his PTSD out of the box he had learned to keep it in. iirc, he never made a war movie. I remember him in one movie that was set during the war, but it was about him building a road. He would not touch the bloody stuff that Wayne did. He had seen enough of the real thing.

Clark Gable was in the service. Ronald Reagan learned how to make propaganda in the Army. Richard Nixon, from a Quaker family, was in the Navy. LBJ, who had been a Congressman since 37, made a show of being in the Navy.

But not Wayne. He hid behind the studio honchos.

Steve