Organized at Rockland, Me., May 8, 1861. Leaving the State on June 20th, it went into action, a month later, at First Bull Run. In September, 1861, a mutiny occurred in the regiment, which resulted in the transfer of about 100 men to another command. The men mutinied because they had enlisted for three months, or supposed the regiment was a three-months one, and so objected to being held for three years. Similar irregularities on the part of recruiting and mustering-in officers had become a frequent cause for complaint throughout the Army. In this case Company H was disbanded, and its place filled, in November by a new company of recruits. The regiment entered upon the Peninsular campaign in Birney Brigade of Kearny's Division, Third Corps. It fought in this command, also, during Pope's campaign, its losses at Manassas--including Chantilly--amounting to 14 killed, 85 wounded, and 15 missing. At Fredericksburg, it lost 22 killed, 66 wounded, and 32 missing; at Gettysburg, 11 killed, 59 wounded, and 74 missing. In 1864, the division was transferred to the Second Corps. In the battle of the Wilderness the regiment was badly cut up; 32 were killed, 136 wounded, and 3 missing. The Fourth Maine lost three Majors killed in action: Major Pitcher was killed at Fredericksburg; Major Whitcomb fell, mortally wounded, at Gettysburg, and Major Grey was killed at the Wilderness. The term of service of the regiment expired on the 15th of June, 1864, when it was ordered home for muster-out, and the rccruits remaining in the field were transferred to the Nineteenth Maine.