The Regiment was organized in Augusta, Maine on September 7, 1861. The new soldiers signed three- year enlistment papers. After election of officers, the regiment traveled on September 10, 1861 to Hempstead, N.Y., and subsequently to Fort Monroe, Virginia. The Regiment formed a part of General Sherman's expedition to Port Royal, South Carolina, which sailed on October 29, 1861. On November 8, the expedition landed at Hilton Head, S.C., where for several months they were engaged in the construction of breastworks and other fortifications. On May 1, 1862, the Regiment moved to Tybee Island and took part in the attack and capture of Fort Pulaski. Large detachments of the Regiment were ordered to man several batteries engaged in the bombardment of the Fort.
Shortly afterwards, the Regiment was stationed at Hilton Head and Beaufort, S.C., for the most part, in doing guard duty at both locations. On March 19, 1863, the Regiment was ordered to Jacksonville, Florida, which they occupied after a spirited engagement with the enemy. On the 25th they engaged the enemy while on reconnaissance on the railroad line towards Baldwin, Florida. The encounter resulted in two soldiers killed and one severely wounded. On March 29, the Regiment was ordered back to Beaufort to make preparations for the expected attack on Charleston, S.C. On April 3, 1863, they embarked for Stone River, where they lay on board transports during the bombardment of Fort Sumter on April 7, after which they returned to Beaufort arriving on April 12, 1863.
Subsequently, they were again ordered to Charleston, but went no farther than Hilton Head, where they remained until November 14, 1863. Soon afterwards the Regiment returned to Beaufort and remained there until March 2, 1864. On that day sixteen officers and 330 enlisted men, led by Colonel Rust, who had re-enlisted for an additional 3-year term, were granted a 35-day furlough. The remainder of the Regiment remained at Beaufort until April 13, 1864, when the Regiment was transferred to the Department of Virginia. They arrived at Gloucester Point, Virginia on April 16, and were assigned to the 1st Brigade, 3rd Division, 10th Corp, Army of the James under the command of General Butler.
On April 26, the veterans rejoined the Regiment and on May 4, 1864 they moved to Bermuda Hundred, where they took part in all operations of the Army of the James. At that time, the Regiment numbered 782 soldiers, under the command of Lt. Colonel Boynton. On May 16, 1864 they participated in the engagement at Drury's Bluff, the result of which was three men killed, 64 wounded and 39 taken prisoner. The Confederates had made a determined assault along the entire Union front. The 8th Maine Regiment repulsed the attack to their immediate front and held its portion of the line until there was most imminent danger of being surrounded. The Regiment fell back in good order to another position from which the enemy attack was again repulsed. Captain Willis, Lieut. Watts, who was severely wounded, and a great part of those reported missing were captured on the picket line early in the morning while disputing the enemy's advance.
On April 27, they proceeded to White House Landing, then on May 31 to Cold Harbor. Within this short period of time, the Regiment was assigned to the 2nd Brigade of the 2nd Division of the 18th Corp. On June 3, 1864 they participated in the general assault on the entrenched enemy fortifications at Cold Harbor, moving in close column by division through the woods and deploying in the open field before the enemy works. The charge was repulsed. The Regiment was quickly reformed, was immediately ordered to again advance and hold a position on the edge of the field where the column had been repulsed and entrenched under heavy enemy fire. The losses during the attack resulted in 10 men killed, 53 wounded, and 16 missing or taken prisoner. Among the killed were Lieuts. Monroe and Hill. The Regiment remained in Union trenches suffering continual losses until June 11th when it was relieved.
On June 12, 1864 the Regiment was moved to White House Landing, and participated in attacks at Petersburg on June 15-17th. On June 18th an entrenched position of considerable strength on the enemy's extreme left having been carried, and again lost by another regiment of the 2nd Division, the 8th Maine was ordered to charge the position. The 8th Maine succeeded in wrestling it from the enemy, taking 54 prisoners. The Regimental losses were 11 men killed, 39 wounded. Lieut. Stevens was mortally wounded while bravely commanding his company. At this time the Regiment had been reduced to 270 guns.
From this time until August 25, 1864, they remained in the trenches in front of Petersburg under continual fire and engaged in very exhausting duties. On that day the Regiment moved to the opposite side of the Appomattox River, going into works before Bermuda Hundred. On the night of September 28th, they crossed to the north side of the James River with the 18th and 10th Corps and were engaged in the successful assault made the next morning on the enemy's works at Chapin's Farm. On October 27, the Regiment was part of an unsuccessful assault on the enemy's lines near the old battlefield of Fair Oaks, where it suffered high casualties. The assault had been ordered to be made on the enemy's works by a small part of our force, five companies of the 8th Maine Regiment were deployed as skirmishers to lead the advancing column. A large portion of the attacking force was captured, including Lieut. Chase. Lieuts. Kyes, Carr and Ingalls were severely wounded. On the next day they returned to the trenches near Chapin's Farm. On December 5, 1864, upon the re-organization of the 10th and 18th Corps, they were assigned to the 4th Brigade, 1st Division of the 24th Corp. The Regiment was moved near Deep Bottom, taking position in the Fort at Spring Hill.
On December 10, 1864 they lost five men killed and suffered six wounded, in the reconnaissance made by the Confederates under General Longstreet, on the right of the Union lines near Spring Hill. Among the killed was Captain Tozier. The Regiment remained in the trenches near Spring Hill until March 27, 1865. On that day the Regiment proceeded towards Hatcher's Run, arriving the next day and remained on picket duty until April 2. On that day, the Regiment participated in the breakthrough in the Confederate lines during the capture of Forts Gregg and Baldwin. On April 3, 1865, they moved with the entire Union Army towards Burksville, Virginia in its attempt to encircle and contain the Confederate Army. On April 6, they took part in the battle at Rice's Station. From April 2 until April 9, the Regiment marched non-stop for nearly 100 miles. The Regiment, after an all-night march, participated in the short battle at Appomattox Court House on the morning of April 9, 1865. They were positioned in the middle of the battle line on that date, placed adjacent to several Colored Infantry Regiments. General Lee called for a truce at approximately 11 a.m., ending most of the war in Virginia.
Shortly after the surrender at Appomattox Court House, the 24th Corp, including the 8th Maine Regiment, was ordered to Richmond, Virginia where the soldiers performed various duties around that city. They remained near Richmond until August, 1865. At that time, they were ordered to Manchester, Virginia where they remained until November, 1865, when they were ordered to Fort Monroe, Virginia, at which place they remained until January, 1866.
On this date, the Regiment was mustered out of the Union Army by Lieut. M. Harper, Assistant Commissary of Musters. The soldiers then proceeded to Augusta, Maine, where the men were paid and finally discharged.