The Union Corps responsible for holding Little Round Top during the Battle of Gettysburg was the Second Corps, specifically the 20th Maine Infantry Regiment, commanded by Colonel Joshua Chamberlain.

On July 2, 1863, this pivotal hill played a vital role in the Union's defensive position. The 20th Maine endured fierce attacks from Confederate troops, especially the 15th Alabama Infantry. Chamberlain's leadership and creative strategies, such as a downhill bayonet charge, were key in fending off the assaults, securing Little Round Top for the Union, and aiding in the overall triumph at Gettysburg.