[1] After garrison duty at the United States Naval Academy in Annapolis, Maryland, the regiment served with the Coast Division commanded by Maj. Gen. Ambrose Burnside.

According to Charles Walcott, the regimental historian, despite Morse's decades of experience with the State Militia, he was, "entirely destitute of soldierly enthusiasm or spirit, wonderfully ignorant of military drill and maneuvres, and a wretched disciplinarian.

[9] After a brief, but tense, three-day encampment in Baltimore, the regiment moved to the United States Naval Academy in Annapolis, Maryland, arriving on August 30.

While the slave was hidden in a chimney in one of the Naval Academy barracks, Governor Hicks's repeated demands for his return were refused by the officers of the regiment.

[12] As the regiment prepared for departure, Colonel Augustus Morse decided to remain at the Naval Academy, feeling that garrison duty was, according to historian James Bowen, "more to his taste.

Prolonged poor weather and the shallowness of Hatteras Inlet resulted in weeks of delay as the fleet struggled to enter Pamlico Sound.

Finally, just as most of the vessels began to run low on potable water, the fleet entered the sound and made for Roanoke Island on February 5, 1862.

[17] Coordinating with a naval flotilla commanded by Admiral Louis M. Goldsborough, Burnside launched an amphibious assault (one of the first of the Civil War) resulting in the Battle of Roanoke Island on February 7 and 8, 1862.

Moving through swamps and knee-deep water, Reno's brigade, including the 21st, advanced around the Union left flank on the west side of the fort.

During that time, Lt. Col. Maggi, determined to make the 21st as disciplined as a regiment of Regulars, enforced stern standards for drill and dress parades.

Maj. William S. Clark, a professor of chemistry at Amherst College, was promoted to lieutenant colonel and assumed command of the regiment on February 28, 1862.

[2] Following the engagement at New Bern, the 21st was among the regiments selected for an expedition to destroy the Dismal Swamp Canal which would cripple the Confederacy's shipbuilding activities at Norfolk, Virginia.

Gen Jesse Reno assumed the command of the Corps and was ordered to support the advance of Maj. Gen. John Pope's Army of Virginia towards Richmond.

The 21st, along with the rest of the Corps, was quickly transported to Fredericksburg and then marched overland to join Pope's forces on August 14, 1862, in the vicinity of Culpeper Court House, Virginia.

The brigade to which the 21st belonged, now commanded by Col. Edward Ferrero, frequently found itself in the position of rear guard during this movement, skirmishing with the advancing Confederate cavalry.

Pope was seen riding by the regiment, "looking warm and excited",[31] and the men learned that Lt. Gen. Thomas Jackson had flanked the Union army and was now in their rear.

[36] Encountering a body of troops in their front and unable to identify them through the torrential rain, Col. Clark presumed he had found the 51st, ordered the 21st to rest in place and sent officer Lt.

The troops were, in fact, men of Jubal Early's brigade and, before this could be ascertained, the Confederates unleashed a devastating volley on the unsuspecting 21st.

Gen. Lee, emboldened by his victories, invaded Maryland and McClellan moved the Army of the Potomac northwest from Washington to meet the Confederates.

The 21st even was fortunate enough to have a mail call that morning, and the men sat down to read letters from home while fighting raged around the Dunker Church two miles (3 km) away.

Ferrero's brigade held the bluff, however, playing a key role in checking the counterattack, and taking severe casualties in the process.

[47] The 21st crossed the Rappahannock on December 12 via the pontoon bridges that had been constructed by the Union army and spent the night along the west bank of the river.

[48] From this position, the 21st watched an assault by a portion of the II Corps over the open plain leading to heights and were shocked by the carnage that resulted from the failed attack.

[49] Just after this assault, Ferrero's brigade was ordered to attack the heights and the 21st formed a line of battle on the open ground slightly after noon.

[50] The 21st did not reach the stone wall on Marye's Heights but took shelter in a very slight depression in the terrain, remaining pinned in that position until night.

In April, due to the reduced numbers of the regiment (now about 200) several officers, being effectively without commands, chose to resign their commissions, including Col. William S. Clark.

One of the most disastrous for the Union army was the Battle of the Crater during which explosives were detonated in a large mine tunneled beneath the Confederate entrenchments, temporarily creating a gap in their lines.

The 21st managed to advance, mingled with other regiments, to the furthest point penetrated by Union troops but by the afternoon they made the retreat "pell mell" with the rest of Burnside's IX Corps.

The final engagement in which the remaining companies of the 21st participated as an independent unit was the Battle of Poplar Springs Church on September 30, 1864, during which the Union army attempted to extend its lines westward, further encircling Petersburg.

Clark's fame persists in Japan where he is a household name due to the revolutionary western ideas he brought to Hokkaido and the influence he had on the development of the island.