Officials initially thought they might recover five to 10 artillery rounds belonging to the CSS Georgia, which was scuttled by its Confederate crew right before the city fell to Union forces in December 1864.
But they've found more nearly everywhere they turn, with about 145 shells and projectiles recovered, and counting.
But the biggest surprise may have come Tuesday afternoon. U.S. Navy divers, who had already brought up two cannons, were bringing up a third, believing from archaeological research that it was an 8-inch cannon.
"The second it broke out of the water, I looked at Parker (Brooks, a graduate student), and said, 'It's a Dahlgren,'" said Jim Jobling, a project manager with Texas A&M University's Conservation Research Laboratory.
Because the 9-inch Dahlgren weighs about 1,500 pounds more than the 8-inch gun, the divers put it back on the Savannah River bottom, with plans to rig it again for the lift to a waiting barge. "These guys are extremely professional," said Jobling.
The Navy team successfully raised the gun at sunset Tuesday.
Jobling, who is working with the U.S. Army Corps of Engineers, said even with 1,500 artifacts found thus far, officials "have only scratched the surface."
The $15 million removal of the CSS Georgia is necessary for a state and federal harbor deepening project, which will see the channel go from 42 feet to a uniform 47 feet so massive cargo container ships can use the port without relying on the tide.
The large number of artillery shells and the discovery of the Dahlgren, a large defensive weapon that had a crew of 16 and a powder monkey (a boy who carried gunpowder to cannons), have added to the mystique of the CSS Georgia.
Researchers have no blueprints or proven photos of the ironclad -- and they aren't sure how it was put together or even its size. These are some of the mysteries they are hoping to solve in the months and years ahead.
First time above the surface in 150 years
Over the past six months, divers working with the Army Corps of Engineers brought up hundreds of items by hand. Then the Navy was brought in to help with heavy lifting.
Virginia-based Explosive Ordnance Disposal Group Two has been in the water for nearly a month, tasked with salvaging the cannons, artillery rounds, the propeller, engine components and the casemate, which are the sloped, armor-coated structures that housed the CSS Georgia's guns. It can be dangerous duty.
They expect to complete work by September 11.
The ironclad was significantly damaged by dredges clearing the channel, most recently in the early 1980s.
They left behind dredge marks amid the remains of the CSS Georgia, which rests on a slope.
"They are like grooves," said Russell Wicke, a spokesman for the Savannah district
of the U.S. Army Corps of Engineers.
Wicke and Lt. Liza Dougherty, public affairs officer for the U.S. Navy group, said Navy divers kept finding artillery rounds that had rolled into the deep grooves.
"The divers would come down, pull up a cannonball and there would be two beneath it," said Dougherty. The Navy is posting updates on its operations on a Facebook page
The CSS Georgia didn't have enough power to maneuver and effectively trade artillery rounds with any enemy vessels that might approach from the Atlantic Ocean. Instead, the vessel became a stationary floating battery, bristling with artillery pieces. The wreckage rests a couple of miles east of downtown.
The Confederate ship may have had as many as 10 guns, but a few may have been removed before the city fell to forces under Union Maj. Gen. William T. Sherman.
Two were recovered years ago and are at Old Fort Jackson, a fortification very near the CSS Georgia wreck site.
The first of four remaining cannon, a small gun, was raised last week.
"It fires a shell that is about 3 inches in diameter," said Jobling. "It could have been used as case shot, or shrapnel, on ongoing soldiers or sailors in rowboats."
A second gun brought up Tuesday morning is a larger Brooke rifle, similar to one at Old Fort Jackson.
"It's a wonderful piece of the history for the Navy guys to know that once a week (the CSS Georgia crew) did their practice rounds (with the gun)," said Jobling. "It's exhilarating and very rewarding."
Officials were excited about the discovery of the 9-inch Dahlgren, a formidable defensive weapon.
A November 1864 inventory of the CSS Georgia doesn't list the Dahlgren, and that's why officials weren't certain it was there. Now it looks like one was indeed on board.
The fourth cannon was retrieved on Wednesday.
'Tremendous historical impact'
The Navy has about 40 personnel involved in the operations. While only two divers are down at a time, many more help with safety, viewing sonar and other images and assisting in the recovery of artifacts.
"There is an all-hands-on-deck mentality," said Dougherty.
While divers and their support staff concentrate on safety and the job of salvage at hand, she said, they know the recovery of artifacts has "tremendous historical impact. It is impossible to miss."
Archaeologists hope to learn more about how the leaky CSS Georgia was built and operated, and about the daily life of the crew.
Divers have found condiment and wine bottles, pottery, a deck light, cannon sights and musket trigger guards, among the myriad items.
They also found six pair of leg irons, or manacles.
"One of the (Texas A&M University
archaeology) students said, 'Oh my God, slavery,'" said Jobling. Actually, they were likely used to confine and punish CSS Georgia crew members who went AWOL. "They were slapped in irons and were made to shovel coal into the boilers."
"There are a number of incidents and the commander at Fort Jackson said he may need to send the Marines to discipline the crew because they were drunk and rowdy. There was discipline trouble at times."
The crew never got a chance to fire on Federal forces.
is working with the Army Corps of Engineers and the Navy, which owns the ship and its contents, to conserve many of the artifacts for eventual display. The wooden lower hull no longer exists.
Archaeologists have the challenge of preserving portions of the CSS Georgia through chemical and other means, making her iron stable so the remains one day can be displayed. Conservation of selected artifacts and parts will be done at Texas A&M and will take about two years to complete.
Wicke said officials hope museums will express interest in housing and displaying selected parts of the ship and artifacts. "At present, no museums or organizations have made commitments."
The Army Corps is sponsoring a "Raise the Wreck" festival
on Saturday at Old Fort Jackson. The program includes artifacts and relevant displays.
Jobling said he expects more discoveries as the large casemate pieces are removed and even after the U.S. Navy divers leave.
"I know there are going to be significant finds."