A couple of my aunts were nurses in the US Army with service spanning across WWII, Korea and Viet Nam. They were Eisenhower republicans all their lives, despite having grown up in a small, western PA coal town that was decidedly a democrat stronghold from Roosevelt forward.
Dad clung to the democrat party through the first Carter term, but in 1980, he voted republican for the first time in his life based almost exclusively on the Pro-Life platform of the party, and he never turned back.
My grandfather was sort of a bigshot in the local Democrat Party. Walking away was a rather traumatic experience for him. But he had concluded that they had left him no choice.