And Hampton Roads was hardly a blockade runners' port.
The James River potentially was, though, but more specifically the role of the ships of force in a blockade is largely to prevent the sally of enemy heavy units. Such as, just for example, the ironclad being built in Gosport Navy Yard.
Blockading doctrine in the 19th century relies on the following:
- Vessels which do the capturing. These are whatever happens to be the faster, more mobile and (usually) cheaper ships available to you. These are frigates (or lighter) in the sail days or steamers in the steam days, and do not have to be heavy combatants - their job is to stop blockade running vessels.
- Vessels which prevent an enemy sally by ships of force, or an intervention by enemy ships of force which are on the high seas such as by breaking out of another blockaded port. These are heavier ships, better defended and more heavily armed, and if the "capturer" vessels are threatened then they can fall back on the "heavy" ships (which means that the blockaded power cannot take out the blockade simply by snapping up light ships but must fight the heavies).
The position of the
Congress and the
Cumberland clearly places them in the latter category. They are there to bulk out the main combatants of the North Atlantic Blockading Squadron where it is blockading Norfolk.
(If you want an example of this in the Crimean War, you would have squadrons of steam gunboats anchored to ships of the line. The presence of the steam gunboats also allowed sailing vessels to have their bows towed around.)
But there are other sail vessels clearly and explicitly engaged in blockading duty.
The US Steamers Crusader, Flambeau, Norwich, Keystone State, Western World, Sumpter, and the armed sailing vessels Restless and Onward have also joined this squadron and are engaged in blockading duty.' Wabash, Port Royal, 2 February 1862 (series I vol. 12 p.533)
The USS
Pursuit captures the sailing schooner Anna Belle on 7 March 1862 (series I vol. 17 p.184) and is "Blockading St Andrew's and Joseph's bay", 12 March 1862 (series I vol. 17 p.188)
These should suffice to indicate that sailing vessels were
explicitly on "blockading duty", and that therefore the Union used sailing vessels on blockading duty.
In the Pacific, meanwhile, the
Cyane is a sailing ship with 18 guns which is clearly engaged in acting as a cruiser, as is the St Mary's which has 22 guns.