The Last Great Battle of the American West (2009).
Addendum: Here is the other (largely forgotten) part of the Battle at Little Bighorn
To Benteen, this mission felt like a wild goose chase designed to keep him from sharing in any of the glory from the upcoming victory. He didn't send a messenger to Custer, since he was ordered only to do so if he saw Natives. Benteen ordered his men to take a longer-than-normal break for the horses (and the men) before moving on. Despite the order to hurry back after accomplishing his mission, Benteen sauntered on; the horses were capable of a faster gait, but Benteen would not hasten his pace.
Benteen wound up joining Major Marcus Reno (pictured left of Benteen), who was on a bluff after his disastrous retreat; Reno's men had their hands full dealing with attacks from warriors. Major Reno ordered Benteen to wait with him, and for the pack train; Benteen chose to follow the orders of an inferior officer instead of those of his superior, Custer.
Benteen spoke against sending troops towards the (loud) gunfire; he claimed that Custer and his men could handle what they were facing. In the absence of any orders from Custer, Reno made no effort to ride towards the sound of the fighting. Due to alcohol, shock, and a severe lack of command skills, Reno didn't even order reconnaissance to ascertain the situation that Custer and his men faced.
Once on the move, Custer saw that he didn't have nearly enough men to corral a large number of Native civilians, and he was under fire from multiple angles. Custer moved half-way up a rise, and ordered a halt. His idea was to hold on for Benteen and Captain Myles Keogh (pictured, who was ordered to defend the high point above the rise) to provide support. It was at this point that Custer had surrendered the offensive to the Native warriors, and the three companies under Keogh's command at the high point were mostly surrounded, and suffering heavy casualties.
Crazy Horse and White Bull challenged each other to "make a run" (a "Courage Run"); they started the process of cutting off the rest of Keogh's men from joining Custer. Custer didn't have any warriors closer to him than 200 yards, too far to be under direct attack, but he saw that warriors were gathering and closing on his position from all sides.
Custer ordered his men to prepare a skirmish line, but they were still very vulnerable since there was little-or-no cover. Custer ordered all the horses shot, and placed in a semicircle to provide primitive breastworks . . . it was a stark declaration (and admission) of the seriousness of their situation (some historians argue that Custer didn't pace his horses properly, and by this point they were too fatigued to make a run to try and escape).
No one, with the exception of Custer, could really hit what they aimed at (few in the Army or among the Natives could truly claim to be a sharpshooter), but the Natives had far more guns, and by volume alone, they were able to pick off Custer's men on the high ground (since the Natives had no real opportunities for practice, anything beyond point-blank range was guesswork).
A segment from "Son of the Morning Star" (1991 TV Miniseries):
a) Reno's Retreat Across the Little Bighorn; b) Private John Martin & Benteen;
c) Custer Makes His Final Push
Crazy Horse reached the area before the fighting was over, taking down one fleeing soldier. Very soon after the battle, noncombatants (especially Native women) had the job of mutilating the slain U.S. soldiers. They crushed skulls, tore out eyes, severed muscles/tendons, hacked off limbs and heads; the goal was to deny the defeated white soldiers any comfort at all in the afterlife.
The end of the Battle of Little Bighorn ("Son of the Morning Star", 1991)
a) The 1st Segment ends with Custer's death
b) The 2nd Segment ends with inaccurate accounts of what was done to
Custer's body as well as the death of Crazy Horse . . .