Biram Dah Abeid is from the country’s traditional slave caste, the Haratin. Photograph by Emiliano Granado

Two springs ago, Biram Dah Abeid arrived home in Nouakchott, the desert capital of Mauritania. At the airport, he was welcomed by hundreds of supporters, along with his wife and children. Abeid, the founder of the Initiative for the Resurgence of the Abolitionist Movement, is the most prominent antislavery activist in Mauritania, which is said to have the highest incidence of slavery in the world. It was Friday, the holiest day of the week, and Abeid, returning from a trip to Berlin and Dakar, was enraged. Recently, he had helped force the government to put a slave owner in prison, and he had learned that the man was released after less than two months.

Abeid, a forty-nine-year-old man with hooded, intense eyes and a warm demeanor, went to his house, and changed from his Western suit into a traditional Mauritanian bubu, a long, loose embroidered tunic. He was going to lead a public prayer nearby, in Riyadh, a section of the city with rocky lots, narrow sand-bleached streets, and pastel-painted concrete houses. When he arrived, a few hundred people had assembled under a bright sun. Men sat on a wide mat on an empty stretch of street, wrapping their turbans tight to ward off dust. Women and children gathered behind them. Activists, sympathetic residents, and the press had been alerted that this prayer was going to be special.

In 1981, Mauritania became the last country in the world to abolish slavery, while making no provision for punishing slave owners. In 2007, under international pressure, it passed a law that allowed slaveholders to be prosecuted. Yet slavery persists there, even as the government and religious leaders deny it. Although definitive numbers are difficult to find, the Global Slavery Index estimates that at least a hundred and forty thousand people are enslaved in Mauritania, out of a population of 3.8 million. Bruce Hall, a professor of African history at Duke University, said that people endure slavelike conditions in other countries in the region, but that the problem in Mauritania is unusually severe: “Some proximate form of slavery has continued to be a foundation of the social structure and the division of labor within households, so there are many more people who are willing to support it as an institution.” While Abeid was travelling, a well-known imam had given a televised interview. A journalist asked whether slavery existed in Mauritania, and the imam said no. Then why, the journalist asked, had the imam recently given the journalist’s boss a slave girl as a gift? The imam simply smiled.

Many Mauritanian slaves, isolated by illiteracy, poverty, and geography, do not recognize the possibility of a life outside servitude, and part of Abeid’s mission is to make them aware. The job is complicated. Slaves are tied to their masters by tradition, by economic necessity, and, Abeid argues, by a misinterpretation of Islam.

Mauritania is an avowedly Muslim country, and though the constitution endorses both secular and religious law, in civic matters Islamic precepts dominate. But the Koran is ambiguous on the essential question of whether slavery should exist. In much of the world, Muslim scholars argue that the only Islamic basis for slavery is in jihad: after conquering unbelievers, Muslim warriors may take them as slaves, provided that they treat them well. In Mauritania, there is little consensus. Imams who defend slavery often refer to a set of interpretive texts that date back as far as the eighth century. One prominent example is a mukhtasar, or handbook of Islamic law, written by the fourteenth-century Egyptian scholar Khalil ibn Ishaq. According to its precepts, a slave cannot marry without her master’s permission, nor does she have any right to her children; a free man who murders a slave will not be punished by death, but a slave who murders a free man will be; slaves are whipped for fornicating, though a master may have sex with his slave girl; and slaves may not inherit property or give testimony in court.

At Abeid’s public prayer, a member of the Initiative for the Resurgence of the Abolitionist Movement (known as IRA) stood to say that he was against any interpretation of Islam that violated its principle of egalitarianism. An imam spoke against slavery and inequity. Another man called for a Haiti-style slave revolt. As they spoke, a plainclothes policeman jumped up and shouted, “Allahu Akbar! What you are saying is wrong!” Men escorted him away.

Abeid came to the microphone, and reporters pushed voice recorders in front of him. “Today will be a historic day,” he said in Hassaniya, the local Arabic dialect. “We will begin today to clean the faith of Mauritania. We will purify the slaves and the slave owners, because both need to be purified. There is a group of bad people who are guarding Islam and using it however they want, and that group is dividing society, putting some people on top and some people down—not because of what they are doing or who they are but because of the color of their skin. We will stop that today.” The crowd murmured in agreement. Abeid is a theatrical speaker, with an impassioned voice that fluctuates wildly, and a habit of preacher-like pauses between phrases.

Abeid addressed the authoritarian government of President Mohamed Ould Abdel Aziz, a former officer who took power in a 2008 coup. “Start your campaign against me,” Abeid said, his voice rising nearly to a shout. “Say that I am against religion. Write that and say that in your mosques. Give money to your slaves and send them to say that everywhere—that will not help you.” The audience watched, transfixed, as he railed against the authorities. “We don’t have to explain ourselves to them,” he said. “We are not afraid and we don’t need their money. Sometimes we have nothing but water for dinner. But we are not afraid. They are false Muslims, so they cannot evaluate our Islam. No one can have more conviction than us, because we say the truth. If we die, it will be from the front, not the back. We will not run away.”

He called President Aziz an ignorant military man with whom it was pointless to negotiate, and he suggested that religious leaders were little better. For years, Abeid had asked the Supreme Council for Fatwa and Grievances to prohibit slavery; he would not ask anymore. IRA would free slaves on its own. “Where are my books?” he said, snapping his fingers. Earlier that week, Abeid had sent IRA leaders to the market to buy a number of books that interpreted Islamic law. “These books justify selling people, they justify raping people,” he said. “We will purify the religion, the faith, and the hearts of Mauritanians.” He held up a red hardcover with intricate embossing. “What the Prophet says was hidden by these books, which are not real words from God,” he said. “These old books give a bad image of Islam. We have no choice but to take this step.”

One of Abeid’s bodyguards dropped the books into a cardboard box and doused them in lighter fluid. The crowd was on its feet, peering at the spectacle. No one had expected this. Defacing the holy books of Islam is a crime of apostasy, punishable by death. Abeid set the books on fire.