Here is a drawing from a picture on Wikipedia of Mr. Cooper:
You can see a quote from The Prairie (click on picture to enlarge). I'm getting fairly close to the end of this book. All I need is a few more stops to wait for the wife to shop. At this point in the story Hard Heart, the Pawnee, and Mahtoree, the Sioux, are battling it out on a little island in the middle of the river with the other Indians and Whites watching. It appears that Hard Heart has the upper hand at the moment, but it isn't over yet. The arrival of the Pawnees on the other side of the river from the Sioux drew enough attention that the white prisoners and Hard Heart could escape their Sioux captors, but Hard Heart didn't want to leave without returning and offering to fight, even though the Pawnees were outnumbered, and so the two chiefs are duking it out. I await the outcome with anxiety and my heart thumping fast.
As for the quote, I can see Doc Holliday responding to that question by Wyatt Earp, "It was your turn to shoot, Wyatt."
I haven't been able to keep up with all the blogs lately due to other stuff, but I'm still here and will soon be back to normal, I keep hoping.