Ok, at this time period the "Standard American English" used by the elite was an affluent east coast accent and not what you think of today as being proper speech from an educated person. In fact our "Standard American English" is closest to a mid-western American accent which would have been seen as much "lower" and more "improper" accent. What is believed to be "Standard English" has changed over time and differs from place to place as well. But Patton almost certainly was taught to speak that way as "proper" and learned to loose whatever accent he grew up with.

cause he was actually from vermont not california