Daryle Williams was emotionally torn, pushing the decision right up against deadline. As a history professor at the University of Maryland, Williams had been researching the slave trade in 19th-century Brazil when he came upon two newspaper ads featuring runaway Africans. One mentioned a mother, Sancha, escaping with her two sons — Luis, 9, and Tiburcio, 4 — in 1855. The other referenced a young woman, Theresa, who fled with her nursing daughter in 1842.

Tasked with entering his findings into what has become part of a groundbreaking new public slavery database, Williams was unsure about what to do. Should he create a separate line for the baby, even without a name?

“From one database perspective, I could have erased her” from the record, Williams said. And yet, even anonymous, the baby ”was part of the lived historical experience. … She was important for Theresa. She should be important for us as well.”

In mid-November, Williams carved out a spot — an act of hope that over time and with the labor of others, the baby’s identity might one day be revealed.

That infant girl, one tiny dot in the vast constellation of Africans swept into the transatlantic slave trade, is included in a massive project aimed at illuminating the lives of the 12.5 million Africans, and their descendants, sold into bondage across four continents.

Enslaved: Peoples of the Historic Slave Trade, a free, public clearinghouse that launched Tuesday with seven smaller, searchable databases, will for the first time allow anyone from academic historians to amateur family genealogists to search for individual enslaved people around the globe in one central online location.

It launches four centuries after the first enslaved Africans arrived on the shores of the English colony of Virginia in 1619. By then, the transatlantic slave trade was already more than a century old.

Directed by data scientists at Michigan State University and four principal investigators, including Williams at U-Md., the project debuted with information about 500,000 named enslaved people and their circumstances, collected by some of the world’s foremost historians of slavery. More records of enslaved people, ethnic groups, populations and places will be entered over time as partnerships are forged with academics, archives, museums and other repositories of information.