Robert Flemming saw it first.

He was standing bow watch on the USS Housatonic, scanning the water between his ship and the dark silhouette of the South Carolina coastline.

A waxing moon cast a faint light across the ocean, and he could just make out the black mass of Fort Sumter nearly six miles distant.

Flemming, a free black Union sailor, often took the starboard bow watch - for all there was to look for. The Housatonic held the northernmost flank in the South Atlantic Blockading Squadron just off Sullivan's Island but, by 1864, it didn't see a whole lot of action.

The ship's role was to intercept blockade runners that tried to sneak into the harbor, but those were few and far between anymore; everyone knew Charleston was nearly a lost cause. Most nights, Flemming saw nothing more than random flotsam and jetsam. Life aboard the Housatonic was about as dull as it got in the Civil War.

It was nearly 8:45 p.m. when Flemming spotted something on the water about 500 feet away. The object was about 22 feet long, he estimated, and only its ends were visible. He called out to a deck officer.

"There is something that looks like a log," Flemming said. "It looks very suspicious."

Lewis Comthwait walked over, took one look and said, "It's a log."

"Queer-looking log," Flemming said. He pointed out that this "log" was not floating with the tide, it was moving across it. Comthwait dismissively repeated his assessment.

Flemming asked the man on the portside bow watch to take a look. When C.P. Slade sided with Comthwait, Flemming said they were both wrong.

He said there was "a torpedo coming."

A month earlier, the blockade fleet had gotten word from Confederate deserters that Charleston had a new secret weapon. These men swore the Rebels had an iron boat that could operate underneath the water and plant torpedoes on enemy ships.

And it was coming for them. Rear Adm. John Dahlgren took this intelligence seriously and told his ships to be prepared for an attack. The Housatonic followed Dahlgren's orders to the letter. The ship sat idling that evening, ready to move at the first sign of danger.

But Flemming didn't think anyone on the ship was moving quickly enough.

"If no one is going to report this, I will cut the buoy adrift myself and get ready for slipping (the anchor)," he said.

This declaration forced Comthwait to look again, this time using his binoculars. Now the object was much closer - and it was closing.

Comthwait turned and sprinted for the bridge. He had to alert the captain.

This night, Feb. 17, 1864, the Housatonic would finally see some action. Because on that night something was out there.

And it was coming for them.

Dangerous ocean

George Dixon had waited months for this moment.

He had come to Charleston to attack the Yankee blockade with the submarine H.L. Hunley, but after four months Dixon had nothing to show for his efforts but frustration.

"(I)f I could tell you all of the circumstances that have occurred since I came here you would not think strange of my not having done any execution yet," Dixon had written to a friend weeks earlier. "But there is one thing very evident and that is to catch the Atlantic Ocean smooth during the winter months is considerable of an undertaking and one that I never wish to undertake again. Especially when all parties interested at sitting at home and wondering and criticizing all of my actions and saying why don't he do something."

"If I have not done anything 'God Knows' it is not because I have not worked hard enough to do some thing," Dixon wrote. "And I shall keep trying until I do some thing."

The odds were stacked against him. Dixon was on leave from his duty with the 21st Alabama Infantry, commanding a private submarine and navigating the tricky world of Confederate military politics. His leave was almost up, the weather had kept him off the water for weeks, and he had done little to instill confidence in the strange boat that people around town had taken to calling the "peripatetic coffin" and the "murder machine."

The Hunley had arrived in Charleston in August 1863. Locals predicted the "fish boat" would break the blockade. But it had not worked out that way.

The sub sank twice in Charleston Harbor, once under the command of the Confederate Navy, and a second time with its namesake at the helm. Thirteen men had died, all of them Southerners.

When Gen. Pierre G.T. Beauregard reluctantly agreed to give the submarine another chance, Dixon had refurbished the boat, raised a new crew and trained them. By the first week of January he was taking the Hunley out to hunt blockade ships four nights a week. Then foul weather set in, and it lingered for weeks. It was far too dangerous on the ocean for such a fragile craft.

Of course, most people thought it was too dangerous to sail this craft in a creek, much less the Atlantic Ocean. But the Hunley was ahead of its time. Dixon knew it better than anyone.

The submarine was the brainchild of Horace Hunley and James McClintock. Hunley was the financier, a dilettante with notions of becoming a great man. The fish boat was his idea, and he hired McClintock, a New Orleans engineer, to build it.

Their first effort, the Pioneer, worked reasonably well but had to be scuttled when the Union invaded New Orleans.

McClintock and Hunley then moved to Mobile, where they built a second sub. The American Diver was a troublesome boat and proved dangerously faulty on its trial run. It sank under tow in Mobile Bay.

Their third boat was much better. The Hunley, as it was christened, was 40 feet long with a tapering bow and a profile like a shark.

The submarine carried a crew of eight men, seven of whom turned a crank that, through a series of reduction gears, powered the boat's propeller. The captain steered and operated diving fins on its flanks.

The sub had two ballast tanks that gave it the weight to dive. The sub's two ballast pumps were complex contraptions that could move water from one tank to the other, and even suck up any water that got into the crew compartment.

McClintock's basic design elements would be incorporated into future submarines for more than a century, but he was never recognized as a father of underwater craft.

In fact, the Confederates had no patience for McClintock. Less than two weeks after he arrived in Charleston, the Confederates took the boat from him, claiming he did not work fast enough. Within a week, five men were dead.

After the Confederates sank the sub at the Fort Johnson dock, Hunley had convinced Beauregard to return the sub to him. A month later, Hunley died in his own boat - along with seven other men - during a demonstration in the harbor.

Then Dixon took over. He had helped build the submarine in Mobile, sailed it on its first trials, and had desperately wanted to come to Charleston with it in August. It wasn't until Hunley intervened, weeks before his own death, that Dixon was granted leave.

Dixon and William Alexander, who had been in charge of building the sub from McClintock's plans, refurbished the submarine in Mount Pleasant. During the refit, the sub's method of attack was changed at Beauregard's suggestion.

The Hunley had been built to tow a floating contact mine at the end of a long rope. But that proved to be a dangerous, faulty system, so the sub was outfitted with a spar nearly 20 feet long, like many of the ironclads have. The spar carried a contact mine, and the submarine simply had to ram it into the side of whatever ship it wanted to sink.

Dixon wasn't sure what would happen when the mine exploded just over 20 feet from the sub's hull, but there was no way to test it. He simply had to have faith his crew would survive.

Signal fire

On the afternoon of Feb. 17, Dixon was having trouble with the sub's new torpedo system. After taking the Hunley out for two hours of practice in the creek behind Sullivan's Island, he returned to the Battery Marshall dock to make adjustments.

"Lt. Dixon landed and requested that two of my regiment, the 23rd South Carolina Volunteers, go aboard and help them to adjust the machinery, as it was not working satisfactorily," D.W. McLaurin recalled years later. "Another man and I went aboard and helped propel the boat for some time while the lieutenant and others adjusted the machinery and rods that held the torpedo, and got them working satisfactorily."

After that, Dixon walked to the beach, got a compass bearing on the Housatonic and was pleased to see that it had not moved. But it rarely did.

This night the weather would be fine. There would be a little too much moonlight, rendering them more visible than Dixon would like, but he was through waiting.

Just before 7 p.m., Dixon ordered his crew to load up. He told the men at Battery Marshall that when the sub was ready to return he would show "two blue lights" as a signal. The troops would then light a signal fire on the beach that the Hunley could use to steer home.

Then Dixon climbed aboard the Hunley, closed the hatch and sailed into the darkness.

Shooting with no effect

By the time Lewis Comthwait reached John Crosby, the Housatonic's officer of the deck that night, a dozen men topsides had spotted the strange contraption.

Crosby himself thought it was "a porpoise coming to the surface to blow." But he had quickly realized that this dolphin was closing in on his ship's starboard flank. Crosby gave the order to slip the anchor and fire up the engine, then called out to Capt. Charles Pickering, who was in his cabin.

When Pickering arrived on deck, his aide appeared by his side and handed him a double-barreled gun filled with buckshot. The captain ran to the gunwale and got his first - and only - look at the H.L. Hunley.

"It was shaped like a large whale boat, about two feet, more or less, under water," Pickering would later testify. "Its position was at right angles to the ship, bows on, and the bows within two or three feet of the ship's side, about abreast of the mizzen mast, and I supposed it was then finding the torpedo on."

Pickering fired his gun at the boat, aiming for the "two projections or knobs about one third of the way from the bows."

Several sailors were firing on the strange boat, but it appeared the shots had no effect. Most of the men described their target as a "waterlogged plank," and one man mentioned the "glimmer of light" coming from the top of the thing.

When Pickering realized the gunfire was having no effect, he called out to the engine room to "go astern faster." By then the torpedo boat was only a few yards away from the ship. Crosby ordered the crew to move toward the bow, away from the impact.

Pickering turned to run for the bridge, but as soon as he took his first step, the deck was no longer there, and the world went silent.

Crosby said it felt more like a collision than an explosion.

When the Hunley rammed the Housatonic with a torpedo packing 135 pounds of explosives, the blockade ship had barely begun to move. Crosby said there was no smoke, no flame or "sharp report."

There was simply a feeling of pressure, and the Housatonic blew up.

The Hunley struck the Housatonic on its rear starboard quarter, just below the curve of the hull. The blast knocked the warship off its keel, lurching heavily to port. It heaved over in a death lurch, a hole in its flank 10 feet wide. One sailor looked over the gunwale and saw a couch float out of the hull. The Housatonic was sinking fast.

Hunley disappears

There was chaos on the water.

The blast knocked several Housatonic sailors into the ocean, and others lay covered in deck debris. Some climbed into the rigging to avoid the frigid seawater.

John Crosby and four other sailors eventually launched one of the Housatonic's few surviving lifeboats and set out to pick up survivors.

While Crosby was fishing disoriented men out of the water, he heard Pickering call to him from the rigging. He first asked Crosby to come get him, then ordered his officer to pull for the Canindaigua, a blockade ship about two miles away.

Crosby met the Canindaigua en route - another dinghy from the Housatonic had reached it first and the ship got underway immediately.

Through the confusion, no one thought to keep an eye out for the boat that had done all this damage. The Housatonic crew members were too focused on survival to look for the fish boat. But they had nothing more to fear on this night.

The Hunley had vanished.

Within an hour of the attack, rescue boats were pulling the Housatonic's survivors out of the water - and out of the doomed ship's rigging. They were lucky. Out of a crew of 155 men, only five died that night. A few others, including the captain, suffered serious injuries.

Two weeks later, the U.S. Navy would hold a court of inquiry on the deck of the USS Wabash. Over a week, 18 members of the Housatonic crew would recount the first successful submarine attack in history.

Robert Flemming was one of the last men to testify, and he recalled that about 45 minutes after the attack he saw the Canindaigua steaming toward the sunken ship. But he saw something else as well.

"I saw a blue light on the water just ahead of the Canindaigua, and on the starboard quarter of the Housatonic," Flemming said.

At the time, no one recognized the importance of this observation.

The troops at Battery Marshall saw the blue light too, and they lit a signal fire as Dixon had requested. But the Hunley never returned.

The U.S. Naval Court of Inquiry would finally conclude that the Housatonic crew had responded appropriately, that there was nothing more they could have done. The ship, and the entire incident, was written off as the price of warfare.

For months, the blockade fleet would remain on alert, ready for the next attack from the strange torpedo boat. The Charleston newspapers concocted an elaborate ruse to fool the Yankees, reporting several times that the Hunley was ready to strike again.

In truth, no one in the city knew what had happened to the fish boat. It was lost, and with it went their last hope of breaking the blockade.

Charleston would limp along for another year. Then, on the one-year anniversary of the Housatonic's sinking, the Confederate military abandoned the city.

The war was over for Charleston, and no one would see the Hunley again for more than a century.

Reach Brian Hicks at bhicks@postandcourier.com