At a bend in the Mississippi River, beneath the chocolate-brown water, archaeologists have come across a surprising find: a sunken Civil War gunship that played a key role in the Battle of Mobile Bay.

The USS Chickasaw -- brainchild of engineering genius James Buchanan Eads -- was recently rediscovered in a graveyard of shipwrecks in the area known as Carrollton, once a town upriver from the French Quarter.

"It was designated as Shipwreck Number 2," said Duke Rivet, a state archaeologist. "They had a total of 19 shipwrecks there."

The Chickasaw, which is now the only known Milwaukee-class ironclad river monitor left, was put to rest in 1944 at that spot on the river, fading into memory along with other outdated and unusable vessels and barges.

The story of the USS Chickasaw is one of fame and ignominy.

With the onset of the Civil War, President Abraham Lincoln spoke with Eads about designing a fleet of new gunships -- the steam-powered ironclads Eads had long championed.

In 45 days, Eads built his first ironclad, the St. Louis. The Confederacy soon launched its own ironclads, changing the face of the Civil War's battle over the rivers and bays of the country.

Eads, an energetic and self-taught young man who turned his inventions into moneymaking enterprises, became renowned after the Civil War when he built a 520-foot-long steel bridge over the Mississippi at St. Louis, completed in 1874.

His fame was bolstered when he used his knowledge of the Mississippi's mysterious ways -- as a young man he'd spent years walking the river's bottoms in diving bells in his vessel salvage business -- and built a navigation channel from the mouth of the river to the Gulf of Mexico.

"On his death bed, Eads said something to this effect: 'I can't die, I have too much to do.' That sort of gives you an insight to his personality," Rivet said.

Six months after being commissioned into the Union navy in February 1864, the Chickasaw entered the Civil War as one of four monitors covering Rear Adm. David Farragut's entry into torpedo-filled Mobile Bay.

After a fierce battle at Fort Morgan, the fleet made it into the bay to face the CSS Tennessee, a Confederate ironclad. In the ensuing battle, the Chickasaw was credited with hammering away at the Tennessee with its guns.

At the end of the war, the Chickasaw saw no more action and the Navy decommissioned it in 1874. In the ensuing years it was made into a coal ferry and later it carried railroad cars across the Mississippi in New Orleans. It was fitted with side-wheel propulsion.

"The propeller shaft is the only thing that looks like it did under Eads," said archaeologist Joan Exnicios about what remains of the Chickasaw.

During World War II, the country kept the heavy-duty Chickasaw around just in case German saboteurs destroyed New Orleans's Huey P. Long Bridge across the Mississippi, said Exnicios, who works for the U.S. Army Corps of Engineers in New Orleans.

The vessel was never needed to carry goods and trains across the river again, and its owners sank it.

"It sorted of faded from memory after that," Rivet said.

The Chickasaw was rediscovered during recent survey work by the Corps of Engineers to stabilize the bed and bank of the Mississippi near the shipwreck graveyard.

There are no plans to raise the vessel, but rock will be placed around it to keep the vessel from moving.

"Preservation in place is the number one preferred route that they go," Exnicios said. Officials said raising the vessel would be too costly.

But with the mind of Eads behind its design, its storied war record and its status as the last Milwaukee-class monitor, officials are hopeful to get the ship on the national historic registry.

In the Battle of Mobile Bay, the Chickasaw, right foreground, helped disable the Tennessee, center foreground.An undated artwork captures the Chickasaw at sea during its Civil War heyday. The Union ship was recently found on the bottom of the Mississippi River.