Interesting comments that echo what my Dad told me. When he was drafted out of a factory in 1942, he was a strong Democrat and New Dealer. It was his experience in the Army that eventually led him to conservatism.
Problems arise when you have politics within the military........
IMHO
I have read studies that say just that; military service tends to be reflected in older adults who are more conservative or at least patriotic. Whether it is causal I am not sure. It may just be that the liberals are more likely to make the effort at avoidance.