This Regiment was organized as three years troops, as other like commands in the United States service. It was constituted December 25, 1863, of four Companies before known as The Hoffman Battalion," raised in 1862, to which were added six new Companies, mustered in at Camp Taylor, Cleveland, January Sand 15, 1864. The Battalion had been mainly on guard duty at Johnson's Island since its muster-in. In the Fall of 1863, as the result of repeated alarms touching apprehended attempts for the release of the Rebel prisoners at that point, the force on guard was materially strengthened, in Artillery and Cavalry as well as Infantry. January 13, 1864, the First Brigade, Third Division, Sixth Corps, including five Regiments, arrived at Sandusky, of which four Regiments with General Shinier, were stationed on the Island, the other Regiment, with General H. P. Terry, commanding the whole, stopping at Sandusky. April 14, 1864, General Shaler, with three Regiments, left to rejoin the Sixth Corps in the field; other portions of the force leaving for Camp Dennison. Soon after, the six new Companies of the One Hundred and Twenty-Eighth were removed to the Island, the Regiment then being for the first time united as one command, under Colonel Charles W. Hill, who, in May, 1864, succeeded General Terry in command of the Island. Troops of various commands were frequently arriving and departing.

The One Hundred and Twenty Eighth from the first was kept under strict drill and discipline. The condition of the Island, and its docks, roads and barracks, demanded heavy work for the provision of means for defense, for proper quarters, sanitary needs, etc., which gave abundant employment for the troops stationed there. The strength of the Regiment was seriously reduced from May until late in the Fall by detachments sent off and kept away for long periods on special duty, thus devolving guard duty on comparatively a small force.

As the result of constant alarms in regard to raids for the release of the prisoners and of the uprising of these, the construction of three Forts was undertaken by the Government in the Fall of 1864. One of' these was on Cedar Point, mouth Sandusky Bay, opposite the Island; and two on the Island. It was expected this work would he performed by hired laborers, but these were scarce and Colonel Hill found it necessary to employ his men for the work, the larger portion of which was done by them, at most inclement seasons, without extra pay, and at a time when other details made heavy drafts upon them. The result was the accomplishment of service highly creditable to the command.

The often scattered condition of the One Hundred and Twenty-Eighth Regiment was a serious obstacle to due discipline and drill; yet these were maintained in high degree throughout. Many of its officers and men had served in the War, some having been discharged for disability; yet for the particular service of the Island, they were well qualified.