WASHINGTON — On Dec. 3, 1794, a Portuguese slave ship left Mozambique, on the east coast of Africa, for what was to be a 7,000-mile voyage to Maranhão, Brazil, and the sugar plantations that awaited its cargo of black men and women.
Shackled in the ship’s hold were between 400 and 500 slaves, pressed flesh to flesh with their backs on the floor. With the exception of daily breaks to exercise, the slaves were to spend the bulk of the estimated four-month journey from the Indian Ocean across the vast South Atlantic in the dark of the hold.
In the end, their journey lasted only 24 days. Buffeted by strong winds, the ship, the São José Paquete Africa, rounded the treacherous Cape of Good Hope and came apart violently on two reefs not far from Cape Town and only 100 yards from shore, but in deep, turbulent water. The Portuguese captain, crew and half of the slaves survived. An estimated 212 slaves did not, and perished in the sea.
On Tuesday, the Smithsonian’s National Museum of African-American History and Culture, along with the Iziko Museums of South Africa, the Slave Wrecks Project, and other partners, will announce in Cape Town that the remnants of the São José have been found, right where the ship went down, in full view of Lion’s Head Mountain. It is the first time, researchers involved in the project say, that the wreckage of a slaving ship that went down with slaves aboard has been recovered.
The story of the São José, like the slave trade itself, spanned continents and oceans, from fishing villages in Africa to sheikhdoms where powerful chiefs plotted with European traders to traffic in human beings to work on plantations in the New World. Fittingly, the discovery of the São José also encompassed continents and oceans. Divers from the United States joined divers in South Africa, while museum curators in Africa, Europe and the Americas pored through old ship manifests looking for clues.
In the end, the breakthrough that the shipwreck was of a vessel that had been carrying slaves came from something unexpected, the iron blocks of ballasts that were used to offset the weight of slaves in the hold.
“The more cargo that you have that is living, the more ballast you need, because live cargo moves and is not as heavy as, say, tubs of molasses,” said Paul Gardullo, historian and curator at the Smithsonian African-American museum. “Ballast becomes a signature for slaving, and a direct corollary to human beings.”
For the museum — set to open on the National Mall in Washington next year — the find represents the culmination of more than a decade of work searching for the remains of a slave ship, any slave ship, that could help tell the story of the 12 million people who were sold into bondage and forcibly moved, over some 60,000 voyages, from Africa to North America, the West Indies, South America and Europe.
Lonnie Bunch, the founding director of the museum, had been looking for such a wreck when he took the job in 2005. “I really wanted something from a slave ship,” he said in an interview. “How hard could that be?”
Exceptionally hard, it turned out, because the museum wanted something original to showcase, and ideally a slave shipwreck that was connected to the United States. Visits to maritime museums in Liverpool and Lisbon for leads on slave ships yielded little. Mr. Bunch heard of a ship that had left Bristol, R.I., in the late 1790s, sailed to Ghana to pick up 144 Africans, then sailed across the Atlantic and sank off the coast of Cuba. But trying to find and excavate that ship proved “too complicated,” he said. Mr. Gardullo, the museum curator, was also chasing leads that went nowhere.
But around 2010, Mr. Gardullo met Stephen C. Lubkemann, a George Washington University anthropologist and maritime archaeologist, who had heard from Jaco Boshoff, a maritime archaeologist with the Iziko Museum in Cape Town, that a shipwreck off the coast thought to be a Dutch merchant ship might be something else. Treasure hunters diving near Camps Bay had identified the ship as the Schuylenburg, which had sunk in 1756.
Mr. Boshoff was coming to another conclusion after multiple dives he and his colleagues had begun in 2010 into waters surging so furiously that they likened them to swimming in a washing machine. Pieces emerged pointing to a different ship altogether.
There in the wreck they found copper fastenings and copper sheathing, which had not come into common use on ships until later in the 18th century. Intrigued, Mr. Boshoff began to dig into archival records, particularly those relating to the Dutch East India Company from 1652 to 1795.
In 2011, as he was poring through the Western Cape Archives Repository that is part of the South African National Archives network, Mr. Boshoff found a critical document: a record from the inquest of the captain of the São José, describing what happened on Dec. 27, 1794, when the ship went down.
The document, which is in Portuguese and paraphrases the inquest testimony of Capt. Manuel João, is chilling. The ship had hugged the shoreline to protect itself from strong winds, but was so close to land that it crashed into rocks and became stuck on two reefs in turbulent surf. It began to come apart right where the treasure hunters had found what they believed to be the Schuylenburg.
Because the slaves aboard were valuable cargo, the crew and captain tried to save them. Some were sent to shore in a barge, according to the testimony, but the strong surf prevented the barge from returning to the ship to pick up more slaves. Hours passed.
Those aboard “made ropes and baskets,” the testimony said, according to an English translation, “and continuing like this were able to save some men and slaves until 5 in the evening, when the ship broke to pieces.” But by then, only half of the slaves on board, along with all of the crew, had been rescued. Some 212 slaves died. The document refers to the crew members as “men,” but not the slaves.
“The slave owners had a vested interest in people surviving,” Mr. Lubkemann said — people who were considered cargo, in much the manner today that sellers would consider livestock being transported as cargo. “It’s like you have a barrel of apples, and you don’t want them to spoil,” he said. “It’s a horrible analogy but that’s how the owners viewed them.”’
The captain’s testimony led researchers in Mr. Lubkemann’s Slave Wrecks Project to comb Portugal’s national shipping archives for more information about the São José. By 2012, they had found the ship’s manifest, which detailed the São José’s departure from Lisbon in April 1794, bound for Mozambique Island, just off Mozambique in East Africa, where the slave trade had expanded from the more heavily trafficked coast of West Africa.
Included in the manifest was what turned out to be the most important clue in the search: The São José had left Lisbon with 1,500 iron blocks of ballasts.
From there the hunt moved to Mozambique, where in 2013 researchers combing through government archives unearthed a document dated Dec. 22, 1794, about 20 days after the ship left Mozambique Island. The document confirmed the sale of a man who was taken from the mainland to Mozambique Island and was aboard the São José.
For the researchers, this was just one man, one slave, out of 400, and he had been given no name in the document save “Black Man.” But it was a record, with a tangible placement of a slave aboard the São José.
By far the biggest piece of the puzzle and the finding that resonated the most with the researchers, had surfaced, literally, in 2012, when Mr. Boshoff and his colleagues were diving in the waters below Lion’s Head. One afternoon, a diver came to the surface saying that he had seen iron blocks buried in the ocean floor.
Mr. Boshoff suited up and slipped into the water to see for himself. There, resting in the sand, were black iron bars, with holes in them.
He understood instantly what they were. Ballasts. Iron blocks of ballasts.
“I’m a scientist, I’m not one for massive amounts of emotion,” Mr. Boshoff said. But, he added, “I knew immediately.”
Iron ballast bars were part of the currency of the slave trade. Ships undergoing those long ocean voyages needed weight to keep them stable, and human beings in the cargo hold do not weigh enough. Their weights go up and down. Some of them die.
So slavers used iron blocks of ballast to counterbalance the variable weights of their human cargo.
More than anything else that divers had pulled up so far from the São José site, from a pulley block to refined finishing nails to encrusted shackles, the iron ballast bars had meaning for the researchers involved. “That people were calculating the weight of human bodies that way — it’s difficult to imagine,” Mr. Lubkemann said.
So far, no skeletons or even partial remains have been found in the wreck.
On Tuesday, when Mr. Bunch of the Smithsonian’s African-American history museum will join his counterparts in Cape Town to announce the discovery of the São José, there will be a memorial service near the site where the ship went down. Divers will place soil from Mozambique Island on the underwater site to memorialize the graves of the 212 drowned slaves.
The officials will announce that recovered objects from the ship, including iron ballast blocks and encrusted shackles, will go on long-term loan to the African-American museum in Washington, from Iziko Museum, which remains the primary owner of the remnants. Mr. Bunch will talk about his recent visit to Mozambique Island, to a fishing village that once held slave pens.
In the interview, he said he was gratified that he had finally found a slave shipwreck for his museum. “I wanted to find a way for people to remember all those nameless people who died crossing that Middle Passage,” he said, referring to the middle leg of the triangular voyages of European ships that sailed to Africa to collect slaves, transported them to the Americas in exchange for raw materials, and then took the raw materials back to Europe.
The space in the museum for the items pulled from the sea, he said, will include recordings of voices describing the slave trade — “a place,” Mr. Bunch said, “for you to mourn and to remember.”
Part of the remembrances, he hopes, will focus on the slaves of the São José who did not die at sea on Dec. 27, 1794. Those people — more than 200 of them — survived the wreck and made it to shore.
And there, within two days, they were sold again.