Fort Pulaski was built by the U.S. Army to protect Savannah from attack, but no one ever dreamed that it would be attacked by the U.S. Army.
The fort was built at the mouth of the Savannah River on Cockspur Island. Much of the early work was done by young Lieutenant Robert E. Lee, recently graduated from West Point.
The fort was completed in 1847 with thick walls that could mount 147 cannons. With civil war looming in early 1861, Georgia Governor Joseph E. Brown ordered Savannah volunteer militia to seize the fort from the federal government. It was a bold move considering Georgia was still in the Union.
In the spring of 1862, the U.S. Army laid siege to the fort using rifled artillery for the first time in history, and the supposedly impregnable fortress fell in 36 hours, cutting off river traffic to Savannah.
Military engineering in the way fortifications were built and assaulted was never the same after Georgia seized Fort Pulaski on January 3, 1861, Today in Georgia History.