Trivia: Virtually all of the extras who play soldiers in the film were members of Civil War Re-enactor groups who not only freely donated their time but also supplied their own uniforms and equipment. This ensued that the film-makers did not have pay for their own extras and that they could stage the massive battle scenes without blowing the budget.
Trivia: During Pickett's charge, Armistead's brigade gets caught at a wooden fence. There is a close up of one of his aides rallying the men and getting shot. If you look closely you will see it's Ted Turner, who bankrolled the movie.
Trivia: Ted Turner's brief appearance is not the only notable cameo in the film. During the artillery bombardment on the Union positions prior to Pickett's charge, Union General Hancock is seen calmly riding through the barrage. A young officer begs him to come down and take cover. The officer is played by Ken Burns, the filmmaker who produced the acclaimed documentary series The Civil War.
Trivia: George C Scott was to play Robert E Lee, but had recurring health problems and Martin Sheen took over on very little notice.
Answer: Yes. After the 2nd Maine Infantry was disbanded, there were 120 men with 1-year of service left. They mutinied because they said they only agreed to fight under the 2nd Maine flag and the Army disagreed. So they were marched under guard to the 20th Maine, led by Chamberlain. Chamberlain was able to convince most of them to fight, even though he was ordered to shoot any who did not fight.
Is there a reason why a few of them refused to fight?
Yes. The same reason why they mutinied.