Declassified Spy Images Just Upended What We Know About the Roman Empire

Archaeologists have discovered hundreds of ancient Roman forts in Syria that “fundamentally challenge understandings” of the contours of the Roman empire, they say in a new study. The archeologists made the discovery while analyzing recently-declassified Cold War spy satellite observations that have become critical to such research in recent years.

A century ago, a Jesuit priest and WWI pilot named Father Antoine Poidebard undertook one of the earliest-known aerial archaeological surveys. Flying over Iraq, Syria, and Jordan, Poidebard mapped hundreds of undiscovered Roman forts that researchers have since believed to be the Eastern frontier of the ancient empire. 

Now, researchers Jesse Casana, David Goodman, and Carolin Ferwerda from Dartmouth College have analyzed declassified footage from the U.S.’s CORONA (1960-1972) and HEXAGON (1970-1986) spy satellite programs that they say redraws and expands the edges of the Roman empire in the same region Poidebard surveyed. 

As the researchers explain in their study, published on Thursday in the peer-reviewed archaeological journal Antiquity, they found 396 undocumented forts or fort-like buildings in the area stretching from western Syria to northwestern Iraq. They report that Poidebard found 116 forts in the same area, making their contribution significant. They also contend that the distribution of these forts clashes with Poidebard’s thesis that the Roman empire maintained a north-south line of defense in the region. 

“Instead, we show that the forts form a roughly east-west line following the margins of the inland desert, connecting Mosul on the Tigris River in the east with Aleppo in western Syria,” the study authors wrote. 

Cold War-era spy satellite imagery has become a valuable resource for archaeologists in recent years. Another team of researchers said in a 2022 Antiquity paper that CORONA satellite images had become “an integral part of archeological research” over the last 25 years, particularly in “sparsely vegetated regions” like the Middle East. Imagery from CORONA’s successor program, HEXAGON, was declassified more recently, in 2020, and has quickly become just as important as CORONA’s imagery was to researchers. 

Indeed, the authors of the latest study noted that they published an earlier survey solely relying on CORONA imagery, but that HEXAGON’s trove “provides higher resolution data.”

The researchers report that the scale of the new forts they discovered were in some cases stunningly large with sides as long as 200 meters. “Many of these larger sites include extensive remains of outlying architectural features surrounding or within the fortifications, multiple fortified buildings, or large citadels,” they wrote.