When construction began on Fort Pulaski in 1829, its design was considered one of the “most spectacular harbor defense structures” in the United States. It took more than 30 years to complete and belonged to what was called the Third System of coastal fortifications. And according to the U.S. Chief of Engineers at the time “you might as well bombard the Rocky Mountains.”

But something changed just a few months later.

It was early 1862, during the Civil War, when Captain Gilmore of the Union army assembled troops on Tybee Island, Ga., planning to bombard the fort with a mortar battery. An engineer himself, Gilmore had great confidence in an experimental new weapon his men secretly moved into place.

The Confederates weren’t concerned about the growing Union presence, as Tybee Island was outside the effective range for traditional smoothbore cannons of the day. But the fort was no match for the rifled cannon. The new weapon gave its mortar a spin lending the projectile more accuracy, range and penetration power.

Confederate commander Colonel Olmstead surrendered after only 30 hours of battle. And Fort Pulaski was effectively rendered obsolete. Today, it’s a monument to bygone wars and the power of technological innovation.