Why was controlling the ports and harbors in the South so important to the Union and Confederacy both?

isaiah 53: 4-6 and   romans 5: 6-8 speak how jesus was pierced for our transgressions,   crushed for our iniquities and that god demonstrates his own love for us in this: while we were still sinners, christ died for us, and by his wounds we are all healed.   psalm 22: 6-7 and   matthew 27: 39-40   correlate basically by the fact that all of the people who didn´t believe in jesus, were telling him that if he was so powerful as he said he was, he should save himself.     matthew 27: 35 and psalm 22: 18 refers about how they divided his clothes among them   and cast lots for his garment. isaiah 53: 8-9 and matthew 27: 57-60 express the process of the burial of jesus. psalm 22: 15-16 and luke 23: 33-34 speak about his crucifiction, the humilliation of being surrounded by sinners, and asking the lord for mercy for humanity. finally in john 19: 33-35   and isaiah 53: 12 speak about the most important prophecy, the testimony of a living god, who resurrected and buried all of our sins and guilt, for all of us. when he was crucified a man saw a sudden flow of blood and water from his wound, and he gived testimony, for all o us to believe, that he poured out his life unto death,   and was numbered with the transgressors.   for he bore the sin of many,   and made intercession for the transgressors.