The entire class was contracted and designed for coastal and river operations during the American Civil War. However, several ships made significant sea voyages during their lifespans. Some notable feats of ships in the class include: Sassacus and her fight with the Confederate ironclad Albemarle (Mattabesett and Wyalusing also took part but in a lesser role); Metacomet and her capture of CSS Selma during the battle of Mobile Bay.

USS ONONDAGA
Double turreted monitor
Commissioned March 1864, USS Onondaga represented the first double-turreted monitor as originally designed and built, to join the Union fleet. Although she was the only ship of her class, her size, armor and powerful battery combined to make her a very formidable foe. So much was thought of her abilities that in January 1865, Onondaga was the sole monitor on duty in the James River when the Confederate James River squadron, consisting of three ironclads, descended the river from Richmond. They had intended battle but withdrew after sight of the presence of the Onondaga added to their misfortune of having had two ships run aground.

USS ROANOKE
Triple turreted monitor.
Originally USS Roanoke was a square-rigged frigate of the old steam navy and sister to the USS Merrimac (later the CSS Virginia). The Roanoke was converted into a triple turreted sea-going monitor - the first and only one of her kind built during the war. However, the sheer weight of armor and armament in the turrets alone caused her to be somewhat top heavy and was too much for her hull to bear under normal operations. As a result, she was restricted to coastal waters, mainly the Hampton Roads area around Norfolk, VA, for most of the war.

COTTONCLAD GUNBOAT
This group of ships includes a large number of which little or no specific information is available. Generally, they were sidewheeled tugs and transports converted into rams with strengthened bows, wood and cottonbale bulkheads and light armaments. Potential candidates for this group include: Col. Lovell, Gen. Beauregard, Gen. Earl Van Dorn, Gen. Sumter, Gen. M. Jeff Thompson and others.