Wikipedia begs to differ for what it's worth...
Following his teen years in New Jersey, Sinatra was interested in serving his country during World War II. But on December 9, 1941, close to his 26th birthday, Sinatra was classified as 4-F at Newark Induction Center, due to a punctured eardrum he suffered from a difficult forceps delivery. This allowed Sinatra to pursue entertainment, rather than being enlisted in the Army Air Corps.
"Sinatra was classified as 4-F at Newark Induction Center, due to a punctured eardrum he suffered from a difficult forceps delivery. This allowed Sinatra to pursue entertainment, rather than being enlisted in the Army Air Corps."
Yeah, right!