Henry Martyn Tremlett (1833 – March 31, 1865) was a Boston merchant prior to serving four years' active duty during the American Civil War.

Tremlett loved to travel, and after graduation from Chauncey Hall, he indulged that passion, including trips to exotic places like Chagres, Panama in 1850 and Calcutta, India in 1851.

Especially for affluent young students, it was customary in the nineteenth century for them to travel after graduation, often quite extensively, to augment their education with the experience gained from touring the world.

Tremlett was back living with his family at 245 Shawmut Avenue, clearly in the prime of his life with a bright future, but a monstrous squall was forming on the horizon.

A photo of Tremlett taken in Boston by Silsbee, Case & Company portrays a man not large, but fit and trim at the waist, with dark eyes and hair and a thick handlebar moustache connecting to his sideburns.

On April 25, Henry joined the Massachusetts Militia, fourth battalion, at Fort Warren located on Georges Island at the entrance to Boston Harbor.

Lee, a civil engineer in private life, was a classmate of Jefferson Davis at West Point and a veteran of the Florida Indian wars against the Seminoles.

On July 10, 1861, less than three months after his time began at Fort Warren, Tremlett enlisted in the Twentieth Massachusetts Regiment which was forming up at Readville, south of Boston.

The army would remain at Poolesville a full month, assigned to picket duty along the Potomac River, consumed by daily drills, shooting practice, and strict discipline, including no noise after taps.

Ball's Bluff was not a large battle but it was another early Confederate victory and another ugly Union defeat at a time when Washington was growing more and more impatient over the lack of military success.

From April through July, 1862, he was part of an enormous force of approximately 121,000 troops that General George McClellan landed at Fort Monroe on the Virginia peninsula.

Tremlett's regiment fought at Eltham's Landing, Seven Pines, Oak Grove, Mechanicsville, Gaines' Mill, Savage's Station, Glendale, and Malvern Hill.

After the conclusion of the campaign, despite another defeat for the Union, he was promoted to the rank of major and reassigned to Company S of the Thirty-Ninth Massachusetts Volunteer Infantry Regimentunder Colonel P. Stearns Davis.

After some time in the capital, the regiment was charged with its primary responsibility of defending it, as some were concerned that Lee's army might attempt an incursion into Maryland, and if successful, move on Washington.

The Thirty-Ninth was therefore ordered to march up the Potomac River into Maryland and establish camp at Poolesville, the same location from which the Twentieth Massachusetts had launched its ill-fated attack at Ball's Bluff the previous autumn.

Though the frequent storms and cold temperatures were a hardship for the soldiers, not much in the way of fighting occurred, which was typical for both armies as winter was usually a time to regroup, reform, reinforce and stay warm and fed.

Tremlett was promoted to colonel on January 5, 1865[5] and assigned as the new commanding officer of the Thirty-Ninth Regiment, Fifth Corps, which was camped in the center of the Union line outside Petersburg.

On February 5, the Thirty-Ninth and the rest of the Fifth Corps were ordered to march west to Dinwiddie Courthouse and on the next day, to Hatcher's Run, located at the extreme left flank of the Union line.

The Thirty-Ninth was in the forefront of the attack, having been assigned that position until the rest of Fifth Corps could be formed up, but, after initially suffering heavy casualties, the regiment fell back.

The wound was such that he was compelled to suffer the amputation of a leg, and though at first it seemed highly probable that he would recover, his enfeebled system was unable to endure the shock, and he died as above stated.

The six weeks immediately following the battle were spent in the hospital at City Point; thence he returned to Boston, getting there May 9, apparently on the road to recovery, but the setting in of intermittent fever proved to be too great a trial of his strength; his body was buried in Forest Hills Cemetery.

Of him a writer in a Boston paper wrote at the time: His standard of manliness was one of noble action rather than of puling pretension, and his whole life showed him to be a loving son, a dear brother, a kind and generous companion, a devoted friend and a truly loyal man, willing.