Some of his writings have been reproduced on the web, including this one: Jeff Davis Milton. Milton, as you can probably tell by the name, was born in the late Confederacy, in 1861, son of the Governor of Florida. Here's part of what Skeeter Skelton had to say about his career.
In 1904, Jeff was appointed to the unique position of Mounted Chinese Inspector. This was a job under the Immigration Service, then part of the Department of Commerce and Labor. The Border Patrol had not yet been organized, and Milton’s commission came directly from President Theodore Roosevelt. Hordes of Chinese were being smuggled out of an antagonistic Mexico into the U.S., which prohibited their entry.
The point to remember here is that people came all the way from China to cross the Mexican border, because the "antagonistic" Mexican government didn't give a damn. Can you think of any modern parallels?
Here's another one which may interest Vdare.com readers:
[In 1919]was assigned to assist in guarding a boatload of Russian radicals comprised of Emma Goldman and her followers on their deportation to Russia. Jeff lusted for trouble and stocked up on extra ammunition, but to his disappointment, the crossing was tranquil.
The Miltons of Florida claimed to be descended from the author of Paradise Lost, so I can't resist the temptation to say, (after Wordsworth) "Milton! thou shouldst be living at this hour: the Border hath need of thee."