William S. Clark
After the battle, the 21st took up camp in the former Confederate fort, remaining there for nearly a month. 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. After the near mutiny of one company, Maggi submitted his resignation. 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.