The 20th Maine was a volunteer infantry regiment that served in the Union Army during the American Civil War. Formed in 1862, it was primarily composed of soldiers from Maine and is best known for its role in the Battle of Gettysburg. Under the command of Colonel Joshua Lawrence Chamberlain, the 20th Maine played a crucial role in defending the left flank of the Union line on July 2, 1863. Their successful defense at Little Round Top helped secure a pivotal victory for the Union forces, contributing significantly to the overall outcome of the battle.