If one treats it as a Fifth Corps story and not the story of the battle, and also remembers it is a novel, then Killer Angels is a fairly accurate description of what transpired on a small part of the stage.

However, the focus on the 20th Maine gives the impression that they were conducting a somewhat independent operation. In fact, the fundamental combat unit in the Civil War was the brigade, in this case 20th Maine, 83rd Pennsylvania, 44th New York, and 16th Michigan, in order left to right as they were on the field the 2nd of July. The defense of Little Roundtop was a brigade action by Third Brigade, First Division, V Corps. While 20th Maine was defending the left flank against attempts by Law's Brigade to turn the flank, the 16th Michigan came under heavy pressure from confederate troops who were making progress up the slope on their front. 16th Michigan actually began faltering when the 140th New York of Weed's Brigade (Third Brigade, Second Division, V Corps) was sent on the run just in time to stabilize the situation. Had that not happened, no amount of heroics on the left would have mattered.

Also, the Killer Angel story leaves out one vital item. Chamberlain detailed one company to set up on the other side of the swale that separates Little Roundtop from Big Roundtop. There they were joined by a group of sharpshooters who had been skirmishing with Law's Brigade on the right flank of Longstreet's Corps. The quantity and accuracy of their fire had induced Law's two right hand regiments to pass all the way up to the summit of Roundtop to ascertain whether the federals were there in force. By the time they reached the actual Union flank they were already well tired out, and when they attacked 20th Maine, they found themselves under fire from the front and from the augmented company across the swale shooting into their flank and rear.

I think the reason Chamberlain has gotten so much attention is that he was himself a very literate man who communicated well. An exerpt from his official report: "It was imperative to strike before we were struck by this overwhelming force in a hand-to-hand fight which we probably could not have stood or survived. At that crisis I ordered the bayonet. The word was enough. It ran like fire along the line, from man to man, and rose into a shout, with which they sprang forward upon the enemy, now not thirty yards away. The effect was surprising..."

You just gotta love a guy like that.
s'Curius