The famous Union Colonel who commanded the 20th Maine was Joshua Chamberlain.

In the Battle of Gettysburg on July 2, 1863, Chamberlain was instrumental in the defense of Little Round Top. His leadership and strategic insight were key in fending off numerous Confederate attacks. Notably, Chamberlain made the daring choice to lead a downhill bayonet charge, which played a significant role in maintaining the Union's position. His efforts not only led to a crucial defensive victory but also established him as a legendary figure in American military history.