Mysterious Mexican wreck was an illegal slave ship

Scientists in Mexico have identified the wreck of La Union, a Mayan slave ship.
Scientists in Mexico have identified the wreck of La Union, a Mayan slave ship. (Image credit: INAH)

A sunken ship discovered near Sisal, Mexico, holds the secrets of a 19th-century tragedy.

Three years after the ship's discovery, archaeologists have confirmed its identity as an illegal slave vessel. The steamer was carrying Mayan captives to work as slaves in the brutal sugarcane fields of Cuba in 1861, months after the forced removal of the Maya from Mexico had been made illegal. The ship caught fire and sank, killing dozens of passengers and crew and an unknown number of enslaved Maya.

According to the National Institute of Anthropology and History (INAH), the sunken steamer La Unión was first discovered 2 nautical miles (3.7 kilometers) from the Yucatecan port of Sisal in 2017. At first, the identity of the wreck was a mystery; archaeologists dubbed it "Adalio" after the grandfather of the fisherman Juan Diego Esquivel, who introduced the archaeologists to the site.

Related: The 25 most mysterious archaeological finds on Earth

Shipwreck detectives

It took three years to map, analyze and identify the wreck. Archaeologists recognized that the ship's boilers and paddle wheels were a type of technology that dated to ships built between 1837 and 1860. They also found pieces of glass bottles, ceramics and brass cutlery amid the wreckage.

The next step was a historical detective mission. The researchers searched the archives of Yucatán, Baja California Sur, Cuba, Spain and Mexico to find a ship that would have been in that area and matched the description of the wreck. La Unión proved to be a match.

The steamer was owned by a Spanish company called Zangroniz Hermanos y Compañía, which began trading between Havana, Cuba, and several ports in Mexico in 1854. Officially, the ship carried paying passengers and merchandise such as tanned hides. But the ship also had a darker purpose.

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In October 1860, La Unión was caught in Campeche, Mexico, carrying 29 Maya, the native people of Central America who were conquered by the Spanish in the 1600s. Following the conquest, the Maya and other Indigenous people were often enslaved on plantations, especially those specializing in sugarcane and coffee. The 29 Maya found in 1860 included children as young as 7.

The loss of La Unión

Slavery was abolished in Mexico in 1829. In May 1861, Mexican president Benito Juárez banned the forcible removal of Indigenous people for sale in other nations. But as the story of La Unión shows, the slave trade continued.

"Each slave was sold to middlemen for 25 pesos, and they resold them in Havana for as much as 160 pesos, for men, and 120 pesos for women," INAH archaeologist Helena Barba Meinecke said in a statement.

This human trafficking occurred against the backgdrop of the Castle War, a clash between Indigenous peoples and the upper classes of Spanish descent, who were levying heavy taxes and seizing farmland from the Indigenous population. Captured Mayan combatants were sold into slavery, often in Cuba, according to INAH. In other cases, slavers called "enganchadores" would travel to Indigenous villages and promise citizens that in Cuba, they would be given their own land. Once the villagers reached Cuba, of course, they were instead enslaved.

Historians estimate that La Unión and another steamer called México, both owned by the same company, smuggled 25 to 30 people to Cuba each month between 1855 and 1861.

On Sept. 19, 1861, La Unión's boilers exploded, setting the steamer aflame. Half of the 80 crew members and 60 paying passengers aboard died. No one knows how many Mayan captives lost their lives, as they were listed as cargo rather than passengers.

The conflagration did draw attention to the illicit human trafficking that was occurring right under the Mexican government's nose, according to INAH. After the loss of La Unión, the government increased searches at Mexican ports to stop the transport of enslaved people. 

Originally published on Live Science.

Stephanie Pappas
Live Science Contributor

Stephanie Pappas is a contributing writer for Live Science, covering topics ranging from geoscience to archaeology to the human brain and behavior. She was previously a senior writer for Live Science but is now a freelancer based in Denver, Colorado, and regularly contributes to Scientific American and The Monitor, the monthly magazine of the American Psychological Association. Stephanie received a bachelor's degree in psychology from the University of South Carolina and a graduate certificate in science communication from the University of California, Santa Cruz.