The Union achieved control of the full length of the Mississippi River after the fall of Vicksburg in July 1863. The Confederate Army then became dependent on Florida for most of its supply of beef. By the end of 1863 between 1,000 and 2,000 head of cattle were being shipped to the Confederate Army from Florida every week. As 1864 progressed, Union troops and sympathizers began driving cattle to Punta Rassa to supply Union ships on blockade duty and Union-held Key West, reducing the supply of cattle available to Confederate forces. The increased shipping from Punta Rassa led the Union Army to built a barracks and a wharf there. By one Confederate estimate, the Union shipped 4,500 head of cattle from Punta Rassa.