When Trip violates orders, Shaw is forced to have him whipped...in front of the whole regiment.
More so because when Trip's shirt is ripped off, it's revealed that his back is already a horrific mess of scars from having been whipped as a slave. Even the resident Drill Sergeant Nasty who is set to administer the punishment hesitates at the sight, glancing at Shaw as if to ask Are You Sure You Want to Do That? While the whipping proceeds, Shaw watches every moment, trying to keep a professional face but obviously hurting. Trip staring Shaw down, not making a sound as he's whipped, doesn't make it any easier.
This scene is made even worse by the fact that it's later revealed that the offense for which Trip was whipped (desertion) was in fact a false charge. Trip wasn't trying to desert at all; he was only going to get shoes for the rest of the regiment. This means that Shaw had Trip whipped for a crime he didn't commit.
The burning of Darien, Georgia. Not so much for the civilians (who are rather unsympathetic with their disdain towards "nigger soldiers"), but for the 54th Regiment who are visibly ashamed as they witness fellow black soldiers gleefully loot the defenseless town, and when Shaw reluctantly orders them to set it on fire.
The Colonel's death in battle.
Both Thomas and Fobbes' reaction to Shaw's death. The anguish in their Roaring Rampage of Revenge was very clear.
Trip picking up the flag for the first time — during the last minute of his life.
The regiment gets so close to victory, only to be slaughtered.
After Shaw's parents were informed of his death, the Confederate in charge wrote to them, saying that Shaw had been buried in a communal grave with "the negroes that fell with him," meaning it as an insult. Some efforts were made to recover the Colonel's body, but his parents spoke out against it. His father, Frank Shaw, wrote a letter later saying:
"We would not have his body removed from where it lies surrounded by his brave and devoted soldiers....We can imagine no holier place than that in which he lies, among his brave and devoted followers, nor wish for him better company – what a body-guard he has!"
One detail of the movie disagrees with historical sources. They say that Shaw actually fell inside the fort upon being shot and that his entire regiment attempted entry to be with their Colonel, only to be slaughtered to a man. Arguably a more powerful statement than even the movie made.
Or even better, when the regiment is still in training, they receive news that the Confederate Army had declared that any black man found in uniform will be hanged, as will any white man found in command—there'll be no prisoners. Shaw says the Union Army will allow a discharge for anyone who wants it. The next morning, he asks his friend "How many are left?" When he doesn't answer, the camera pulls back to show that NOT ONE black or white soldier has left. A choked-up Shaw can only say "Glory Hallelujah." Damn straight.
