The assault on and capture of Fort Pulaski is the story of the elimination of Savannah, Georgia as a Confederate seaport. Of equal importance was the North's successful use of rifled artillery against that masonry fort, a technological turning point equal in significance to the much better known development of ironclad ships. The rifled cannon were developed in the mid-1800s and were first used in siege warfare during the attack against Fort Pulaski. In April 1862, three of those formidable new weapons breached Fort Pulaski's walls within thirty-six hours, forcing the garrison to surrender and closing Savannah's port. This is the first modern account of great Federal labors, under terrible conditions in difficult terrain, to erect the batteries which sealed the Savannah River, isolated Fort Pulaski, and finally forced its surrender amidst the Union army's infighting over who should receive credit for the operation.

In 1864, six hundred Confederate prisoners of war, all officers, were taken out of a prison camp in Delaware and transported to South Carolina, where most were confined in a Union stockade prison on Morris Island. They were placed in front of two Union forts as "human shields" during the siege of Charleston and exposed to a fearful barrage of artillery fire from Confederate forts. Many of these men would suffer an even worse ordeal at Union-held Fort Pulaski near Savannah, Georgia, where they were subjected to severe food rationing as retaliatory policy. Author and historian Karen Stokes uses the prisoners' writings to relive the courage, fraternity and struggle of the "Immortal 600."