Fort Pulaski was built between 1829 and 1848 in order to protect the Port of Savannah from enemy navies. Twenty-five million bricks were needed for the construction at a cost of $1,000,000. The fort was deemed impenetrable.
"Fort Pulaski, built by the U.S. Army before the war, is located near the mouth of the Savannah River, blocking upriver access to Savannah. Fortifications such as Pulaski, were considered invincible, but the new technology of rifled artillery changed that.
"The defining events of Fort Pulaski occurred during the American Civil War. In April of 1862, Union troops directed rifled cannon fire at the fort breaching the southeast angle. The quick success of this experimental cannon surprised military strategists worldwide. The accuracy and range of the rifled cannon rendered brick fortifications obsolete. Immediately after capturing the fort, Union Major General David Hunter, an ardent abolitionist, ordered the release of area slaves. Many were recruited into the Union army comprising the First South Carolina Colored Regiment."
Source: National Park Service.
During the siege, which lasted thirty-one hours 5,275 rifled cannonballs were fired at the walls of the fort. When the southeast corner was breeched and cannon fire came close to the fort's powder magazine in the northwest corner, the fort was surrendered. The results of this battle would change the way fortifications were built and the way wars were fought.