In the fall of 1864, a U.S. Navy officer serving in the blockade of Charleston set out on a quest that would consume some men for more than a century.

He wanted to find the H.L. Hunley.

William L. Churchill, executive officer on a gunboat and a diver with much interest in submarine technology, had volunteered to survey the wreckage of the USS Housatonic, a blockader sunk by the Confederate fish boat earlier that year.

But according to letters between Union naval officers recently donated to the S.C. Confederate Relic Room and Military Museum in Columbia, Churchill was looking for a lot more than debris.

"His is also desirous of exploring the ocean bottom in the vacinity [sic] of the ill-fated Housatonic, with the view of finding the Torpedo Boat, which, by mail and clippings, taken from Rebel Journals, may have sunk very near her," Nipsic commander A.W. Johnson wrote to Rear Admiral John A. Dahlgren.

That note, a rare contemporary mention of the Hunley, is part of a set of 27 documents donated to the museum by a private collector. Kristina Dunn Johnson, curator of history at the Relic Room, said the letters offer a view of the war not often found in Southern museums.

"We were especially interested because they were Union letters associated with the blockade," Johnson said. "Even though they are Union correspondence, they are central to South Carolina's wartime story."

The letters, many of which are either to or from Churchill, A.W. Johnson or Dahlgren, date from the early days of the war up to 1869, when Churchill had his own submarine company. Together, they tell the story of one man's journey through the Civil War.

The first letter notifies Churchill of his appointment as master's mate on the USS Susquehanna, a sidewheel steamer. From the deck of that ship, he watched the battle of Hampton Roads, where the USS Monitor fought the CSS Virginia (or the Merrimac) to a standstill. Soon after that, he wound up on the Nipsic, which took part in the blockade of Charleston Harbor.

Dahlgren allowed Churchill to make his survey, and the results have helped tell the Hunley's story.

In his report, Churchill declared the wreck of the Housatonic "worthless" and described the massive amount of damage caused by the 90-pound charge delivered by the sub.

But he did not find the torpedo boat.

"I have also caused the bottom to be dragged for an area of 500 yards around the wreck, finding nothing of the torpedo boat," Churchill wrote. "On the 24th the drag ropes caught something heavy (as I reported). On sending a diver down to examine it, proved to be a quantity of rubbish."

Churchill did not say, however, whether he searched in every direction around the Housatonic. The Hunley eventually was found seaward of the Housatonic wreck, a surprise that bedeviled archaeologists and treasure hunters for 130 years.

"We're lucky Churchill didn't find it during this expedition," said Robert Neyland, head of the Naval Historical Center's Underwater Archaeology branch. " If he had, nothing would be left of the submarine today and it would have been a major loss for history."

When scientists raised the Hunley in 2000, they found a grappling hook that remains unidentified but may have been equipment such as Churchill would have used in his dragging.

As for Churchill, he eventually suffered a fate similar to that of the Hunley. Four years after the war ended, he was killed during an underwater demolition job. His body was lost at sea.

If you go

--The S.C. Confederate Relic Room and Military Museum is at 301 Gervais St. in Columbia, in the same building as the State Museum.

--Open Tuesday through Saturday, 10 a.m. to 5 p.m., and the first Sunday of each month from 1-5 p.m.

--Admission is $5 for adults.

--The Churchill letters are not currently on display but are expected to be on the Relic Room's Web site soon.

--For more information: http://crr.sc.gov/visit/.