The 20th Maine Volunteer Infantry Regiment was a combat unit of the United States Army during the American Civil War, most famous for its defense of Little Round Top at the Battle of Gettysburg, July 1863.
The 20th Maine was organized in the state of Maine on August 20, 1862, with Col. Adelbert Ames as its commander. It became part of Col. Strong Vincent's Brigade of the 1st Division of the V Corps of the Army of the Potomac. The brigade consisted of the 16th Michigan Infantry (with Brady's independent company of sharpshooters attached), 44th New York Infantry, 83rd Pennsylvania Infantry, and the 20th Maine Infantry Regiments. At Gettysburg, the regiment was commanded by Col. Joshua L. Chamberlain. Maj. Ellis Spear took command after Chamberlain was appointed brigade commander in August 1863.
The regiment served at Antietam (held in reserve), Fredericksburg, Chancellorsville The soldiers were quarantined in the rear area due to illness from a tainted small pox vaccine that they had been ordered to have. Other battles included Gettysburg, Rappahannock Station, Mine Run, the Wilderness, Spotsylvania, North Anna, Totopotomoy and Bethesda Church, Cold Harbor, Petersburg, Five Forks, and Appomattox.
The most notable battle was the regiment's decisive role on July 2, 1863, in the Battle of Gettysburg, where it was stationed on Little Round Top at the extreme left of the Union line. When the regiment came under heavy attack from the Confederate 15th Alabama regiment, part of the division led by Maj. Gen. John Bell Hood, the 20th Maine ran low on ammunition after one and a half hours of continued fighting; it responded to the sight of rebel infantry forming again for yet another push at them by charging downhill with fixed bayonets, surprising and scattering the Confederates, thus ending the attack on the hill. The 20th Maine and the adjacent 83rd Pennsylvania together captured many men from the 47th and 15th Alabama regiments. Had the 20th Maine retreated from the hill, the entire Union line would have been flanked, and would have most likely lost the battle of Gettysburg, although there is much debate on the subject. Union morale and support for the war was wavering, due to many defeats. If the Union had lost the battle of Gettysburg the Confederate army could possibly been able to march on to Washington D.C. and end the war. The 20th Maine’s action in holding the hill has been credited with helping to turn the tide of the war.
Recent research has found claims by Lt. Holman S. Melcher that he initiated the charge, although Col. Chamberlain has been credited by most historians for ordering the desperate attack. This action is depicted in the novels The Killer Angels and Courage on Little Round Top, and was subsequently an important scene in the movie Gettysburg.
The 20th Maine marched from Appomattox, Virginia, on May 2, reaching Washington, D.C., on May 12, where it was mustered out of service on July 16, 1865.
The 20th Maine had an initial enrollment of 1,621 men, losing 150 dead from combat, 146 dead from disease, 381 wounded, and 15 in Confederate prisons.