In San Antone, the tension between the two women builds pretty much from the beginning, and the fight occurs within the first 45 minutes. I recall in the scene preceding the fight, Ms. Whelan, playing the role of the jealous, underhanded woman, expresses concern about being bitten by a rattlesnake while she sleeps. The man for whose attention the two women are vying uses a rope to encircle her bedroll assuring her that no snake will cross over it. After he leaves, Ms. Jurado asks out loud, "why one snake would bother to bite another." When she turns her back, Ms. Whelan picks up a knife and moves toward her. Katy turns just in time, to fend off the attack, disarm her and the fight is on. I couldn't find this on youtube and I don't have the patience to bother with Dailymotion and their long ads, so happy hunting.
In Dragoon Wells Massacre, the fight happens near the end of the movie. I don't know when the two women first meet each other, or what causes the tension because I just happened upon it in progress one afternoon many years ago. The fight begins when Ms. Blanchard trips Ms. Jurado who is walking by. Here's a link to the battle, which picks up right after Katy picks herself up from being tripped.
http://www.youtube.com/watch?v=MGcHfnx8iPo
