Constructed as part of the coastal defenses by the U. S. Military prior the Civil War, Fort Pulaski had walls made of brick that were seven feet thick and 35 feet tall. It was surrounded by a moat that was 25 feet wide and the walls enclosed an area of approximately five acres. On January 3rd, 1861, Georgia Militia troops occupied the fort and raised the state flag. Federal forces occupied Fort walker on Tybee Island about one mile away from Fort Pulaski. On April 10th of 1862, Federal forces initiated an artillery bombardment that lasted for 34 hours and launched over 5,000 rounds at Fort Pulaski. On April 11, 1862, the Confederates surrendered Fort Pulaski to the Federals. It would remain in the possession of Federal troops for the remainder of the war and would become a safe haven to freed slaves from the area. Many of the freed slaves would volunteer for the Union Army and form the 1st and 3rd South Carolina Colored Volunteers.