The numbers (80 charging and capturing 4000) are totally out of whack but in essence Joshua Lawrence Chamberlain and the 20th Maine did charge downhill at the 15th Alabama, driving them off and taking prisoners, and he was subsequently (30 odd years later) awarded the Congressional Medal of Honor. He was also present at Appomatox and later Governor of Maine and President of Bowdoin. His career is pretty impressive, and, although it's frowned on here, the wikipedia page on him seems like a reasonably accurate summation of his achievements.

My personal opinion (as a former grad student in US History, Civil War specifically) is that his famous charge that saved the flank on Little Round Top did not turn the tide of the war, as is sometimes implied. No doubt had the 15th Alabama driven the 20th Maine from their positions it would have been a hard time for the Union defenders of Little Round Top, but Union reinforcements were already on the way, and the Confederate attackers were very tired, having already done a lot of marching that day, and did not have food or water. I don't think that they would have been able to exploit a small local success into a general breakthrough into the Union rear. I would also add that Longstreet had very ambiguous feelings about the whole battle and may not have supported a local success on Little Round Top with the weight of his whole Corps, even supposing that he could have been informed of the situation in a timely manner and responded with alacrity (alacrity not really being his style). On the whole, while any victory is a good thing, I don't think that the 100-odd prisoners that Chamberlain took with a bayonet charge saved the Union, or that, had he retreated that the Confederacy would have won the war.

In The Hands Of Providence: Joshua L. Chamberlain And The American Civil War by Alice Trulock isn't bad, although it's some years since I read it so I can't really give it a ringing endorsement.