A whole book has been written on the song family in question:

"I Went Down to St. James Infirmary," by Robert W. Harwood (Kitchener, Ont.: Harland, 2008).

Harwood asserts that cowboy Francis Henry Maynard "copyrighted" the cowboy version in 1876. While supporting Maynard's claim, his biography by Jim Hoy, Cowboy's Lament (2010), makes no mention of a copyright, which would seem highly improbable anyway.

Maynard published a booklet of his verse titled "Rhymes of the Range and Trail" (1911) which included the following:


THE DYING COWBOY

As I rode down by Tom Sherman's bar-room,
Tom Sherman's bar-room so early one day,
There I espied a handsome young ranger
All wrapped in white linen, as cold as the clay.
"I see by your outfit that you are a ranger,"
The words that he said as I went riding by,
"Come sit down beside me, and hear my sad story,
I'm shot through the breast and I know I must die.

Chorus:
Then muffle the drums and play the dead marches;
Play the dead marches as I'm carried along;
Take me to the church-yard and lay the sod o'er me,
I'm a young ranger and I know I've done wrong.

"Go bear a message to my grey-haired mother
Go break the news to gently to my sister so dear,
But never a word of this place do you mention,
As they gather around you my story to hear.
Then there is another as dear as a sister,
Who will bitterly weep when she knows I am gone,
But another more worthy may win her affection,
For I'm a young ranger — I know I've done wrong."

Chorus

"Once in my saddle I used to be dashing;
Once in my saddle, I used to be brave;
But I first took to gambling, from that to drinking,
And now in my prime, I must go to my grave.
Go gather around you a crowd of gay rangers,
Go tell them the tale of their comrade's sad fate,
Tell each and all to take timely warning,
And leave their wild ways before it's too late."

Chorus

"Go, now, and bring me a cup of cold water,
To bathe my flushed temples," the poor fellow said.
But ere I returned, the spirit had left him,
Had gone to is Giver — the ranger was dead.
So we muffled the drums and played the dead marches,
We bitterly wept as we bore him along,
For we all loved the ranger, so brave and so handsome,
We all loved our comrade, although he'd done wrong.


Maynard told a journalist in 1924:

"During the winter of 1876 I was working for a Grimes outfit which had started north with a trail herd [from Texas]...We were wintering on the Salt Fork of the Arkansas river on the border of Kansas....

"One of the favorite songs of the cowboys in those days was called 'The Dying Girl's Lament,' the story of a girl who had been betrayed by her lover...

"I had often amused myself by trying to write verses, and one dull winter day in camp to while away the time I began writing a poem which could be sung to the tune of 'The Dying Girl's Lament.' I made it a dying ranger or a cowboy....

"After I had finished the new words to the song I sang it to the boys in the outfit. They liked it and began singing it. It became popular with boys in other outfits ...and from that time on I heard it sung everywhere on the range and the trail."

Not long after this interview, Maynard told song collector Ina Sires that "he wrote the words to fit the tune of an old song that used to be sung by the cowboys called 'The Dying Girl's Lament,' which was the story of a girl dying in a hospital, and which began like this:

"'As I walked down by St. James Hospital, St. James Hospital so early one day, etc.' The song was accepted by the cowboys."

While Maynard was apparently responsible for *one* adaptation of 'The Dying Girl's Lament,' there's no way to know if he was truly the first to adapt the song to the American West. No text before Thorp's very different (and oddly "literary") one (1908) seems to survive.