Aborigines

For several days, the journey continued as it had before; long, slow, hot, and boring. Five days after you crossed into Arizona, the company saw the Apache for the first time. Two men stood on a small ridge several miles away, watching casually, loosely cradling rifles in their arms. This spurred some mumbling amongst the men. The young ones pulled their Winchesters from their saddle scabbards and verified they were loaded, but you knew better. The Apache were just watching at the moment. They likely wouldn't attack for another day or two, and a bunch of frightened kids with rifles loaded and cocked was a recipe for disaster.
At the front of the column rode the Captain. Beside him were the supply wagons, and behind them rode the soldiers. When push came to shove, the wagons would be moved into a circle for cover, and the men would set up a perimeter within and keep the marauders out of their ranks. Ordinarily you only keep five shells loaded in your revolver, so the hammer rested on an empty chamber, but now that the Apaches were nearby and watching you decide it would be best to load a sixth in.

The next day was very quiet, and you didn't like that very much. No desert birds chirped or even flew about and the only noise was the trodding of the beasts and the silent whisper of the wind through the shrubs. "Captain," you call out, and that's when it happens. Like a ghost in the sand a brown warrior rose and yanked a man out of his saddle, braining him with a club before anybody could react. Instantly ten guns spat lead into his torso and he crumpled mute and still and twenty more warriors came flying down a slope on horses firing their rifles one-handed like pistols. The men on the wagons tried to form a circle but there was no coordination, and the horses were too frightened by the sudden chaos. They bucked and pulled as fast as they could and one of the wagons hit an especially large rock and flipped on its side, spilling the teamsters and the supplies to the ground.
"Keep going!" yelled the Captain, every bit as frightened as the men. "Don't stop!"
You spur your horse viciously, drawing your sidearm, as firing a rifle on horseback was too difficult to do accurately. You fire twice into the attackers but have no idea whether or not you hit any of them. What followed was a violent running fight. The Indians let loose into the crowd of soldiers, dropping several of them. The wagons could not keep up and were left behind and the teamsters were quickly swallowed within the horde. In the dirt lay the bleeding corpses of soldiers and Apaches alike, though the soldiers were far more numerous.
The Apaches covered both flanks, driving the terrified soldiers in one direction. Ahead loomed a canyon. In the canyon were two branching paths, one to the left, one to the right. The troops flooded down both pathways. The Captain and the vast majority of soldiers headed down the right. You needed to pick a path and fast, as the bloodthirsty army behind you was quickly catching up.