Why was controlling the seas important during the Civil War?

Controlling the seas was crucial during the Civil War because it enabled the Union to implement a successful blockade of Southern ports, severely restricting the Confederacy's ability to trade and obtain supplies, arms, and food. This naval dominance facilitated the movement of Union troops and resources, allowing for strategic offensives along the Southern coastline. Furthermore, control of waterways like the Mississippi River was vital for transportation and communication, which helped the Union to split the Confederacy and maintain logistical advantages throughout the war.