During the Civil War, the Union Navy’s primary mission was to prevent the South from marketing her products and to prevent her from obtaining arms. To accomplish this dual mission, the North stationed a considerable number of ships in blockade positions along the Gulf and Atlantic seaboards. The majority of these blockade vessels were small in size as well as firepower. There were two main reasons why the Union used small ships as blockaders. The first reason being that their adverseries likely would be small, shallow-draft vessels with limited firepower, and second, the larger more powerful ships were needed to seek out and destroy the many large, well-armed blockade runners, such as the Alabama and the Florida.
Falero, Jr., Frank
"Naval Engagements in Tampa Bay, 1862,"
Florida Historical Quarterly: Vol. 46
, Article 6.
Available at: https://stars.library.ucf.edu/fhq/vol46/iss2/6