Chamberlain fought for the Union because he wanted to save the Union and because he wanted to free the slaves.
I found this website to be helpful; especially the first couple of paragraphs.
http://people.Maine.com/publius/almanac/encycweb/htm/Chamberl.htm
Union
yes
Union fought Confederate at Manassas (Bull Run) - both times.
Fight off union attacks intil they could survive as a union
The Union
Union
Joshua Lawrence Chamberlain was on the Union side.
Had the Alabamans broken through Chamberlain's 20th Maine Regiment there, Lee might have been able to fight a Battle of Penetration, and roll up the Union line.
Nevil Chamberlain is well known for a public policy of appeasement.
Colonel Joshua Chamberlain from the Union won with a bayonet charge.
The Union officer who led the 20th Maine at the Battle of Gettysburg was Colonel Joshua Lawrence Chamberlain. His leadership and tactical decisions on the second day of the battle, particularly during the defense of Little Round Top, played a crucial role in the Union victory. Chamberlain's heroic actions earned him a Medal of Honor.
Union
Union
The Soviet Union invaded Afghanistan to fight anticommunists.
Union. Lincoln's Mantra was always "Union".
Because union fought to free slaves.
To keep the Union together.