
http://en.wikipedia.org/wiki/Little_Round_Top
Medal of Honour recipient Joshua Chamberlain is one of my heroes -- a college professor (and later governor of Maine) who turned out to be a exemplary leader and soldier.

A few years ago I finally made the pilgrimage to Gettysburg and got to stand where the 20th refused the flank and -- almost out of ammunition and desperate -- made the bayonet charge that secured the left on Day Two. And while I detest what the South represented, I do appreciate the fighting spirit of the Alabama and Texas boys who attacked again and again in terrible conditions.

While there are some historians who dissent, the majority of them conclude that had the 20th not held the line, the Confederates could have rolled up the line as far as Cemetery Ridge by nightfall, all but guaranteeing a victory for the Rebs on Day Three.
The Battle for Little Round Top starts at 2:05:16 (although I would suggest watching all of it) -- great movie. A little over the top at times with the soundtrack, but I really enjoyed Tom Berenger's, Sam Elliott's and Jeff Daniel's performances.
The scene right before at 2:03:30 is pretty intense with John Bell Hood arguing with Longstreet about the pending attack.
"Now sir, if you are ready, why don't you take that hill."
[video]http://www.youtube.com/watch?v=bTcaRk0ZRJ4[/video]