After the formation of the Confederacy and the Battle of Fort Sumter, Congress authorized a massive increase in the number of specialized engineer troops on August 3, 1861, to complement the growing Union Army.

After the unit had been mustered, the Paymaster General refused to recognize the status of the newly formed regiment, and paid them the same rate as infantry.

The regiment sailed for Port Royal from New York Harbor on October 13, 1861, aboard the steamship Star of the South.

[9] Using Morris Island as a staging area, the X Corps could focus on recapturing Fort Sumter, the site of the first military action of the Civil War.

[10] Unable to recapture Fort Sumter, the X Corps under Gen. Quincy Adams Gillmore turned their attention to the nearby city of Charleston.

At the same time there was a request to the department's surgeon to splice three six-foot men together to make the needed eighteen footers.

[12] Serrell assumed personal responsibility and conducted a series of experiments to establish the capability of the soil to support weight.

[13] The "Swamp Angel," an 8-inch, 200 pound Parrott Rifle was positioned in the battery, and the 11th Maine Volunteer Infantry Regiment manned the weapon, firing incendiary shells at the city of Charleston from August 22–23 of 1863.

[16] In the spring of 1864, companies B, C, E, F, H, K, L & M were sent to join Benjamin Butler's Army of the James, and Serrell was again named chief engineer of the Corps.

They participated in the Bermuda Hundred Campaign, building the entire Bermuda Hundred Line, laid many miles of corduroy roads, dredged the Dutch Gap Canal, and constructed the abutments and roads that connected the pontoon bridge assembled by the Engineers of the Army of the Potomac with City Point, Virginia.