What can be concluded from the Union's desire to blockade ports in the South?

A blockade is a military technique that can be used to prevent military materials from reaching an army, preventing exports from getting out of a territory, or to prevent goods from being imported. Blockade's are used as a military technique to weaken the enemy or to cut them off to resources. This is part of the reason why the Union used a blockade against the South in the Civil War.