Cold War spy satellites reveal hundreds of forgotten Roman fortresses in the Middle East

With the help of two American spy satellites – originally intended to keep a close eye on the activities of the former Soviet Union – researchers have now discovered almost 400 previously undocumented Roman forts. The research also sheds new light on the function of Roman buildings in the Middle East.

Researchers write this in the magazine Antiquity. They are based on images taken during the Cold War within the framework of the American spy programs CORONA and HEXAGON. Within these espionage programs, several satellites were launched that kept a close eye on what the Soviet Union was doing and its military position between 1960 and 1986. A large number of the images taken are now publicly accessible, offering scientists the opportunity to analyze these images in search of the contours of Roman forts. They specifically focused on an area that extends from western Syria to northwestern Iraq and is also referred to as the ‘Fertile Crescent’.

396 forts
And the analysis turns out to be anything but fruitless; In total, the researchers found 396 previously undocumented forts in the images. “Our observations are quite exciting and probably only reveal a fraction of what happened in the past,” says researcher Jesse Casana.

Previous research
It is not the first time that scientists have hunted Roman forts in this area. For example, pilot and landscape archaeologist Antoine Poidebard discovered around 116 Roman forts in this region in the 1920s. Poidebard made his discovery from the air; He explored the area from a small plane and saw the contours of Roman forts – much more difficult to see from the ground – appear in various places. What struck him was that these forts were more or less on one line, running from north to south. It led him to the conclusion that the forts were intended to defend the eastern border of the mighty Roman Empire.

Many of the forts Poidebard spotted were probably destroyed or obscured by agriculture and other human activities between the 1920s and 1960s. Nevertheless, Casana and colleagues still managed to identify about 38 of the 116 forts discovered by Poidebard on the images taken by the spy satellites. And in addition to that, they discovered another 396 previously undocumented forts. Some of these must have been large enough centuries ago to accommodate soldiers, horses and/or camels. And judging by satellite images, some forts may even have had watchtowers. Today, little remains of those imposing buildings – sometimes made of stone, mud or a combination of the two – but just enough to conclude from the air that there was a fort there.

Other distribution
Of course it is great to rediscover almost 400 Roman forts. But what particularly fascinates the researchers is how they are distributed across the area. Because while Poidebard – based on the 116 forts he spotted – concluded that they were situated on a line running from north to south, the 396 forts that Casana and colleagues have documented paint a completely different picture. “Our research shows that – contrary to Poidebard’s interpretation – the forts are spread over a huge area stretching from east to west,” the researchers write in their research paper. And this also calls into question the idea that the forts guarded the eastern border of the Roman Empire. “It surprised me that there were so many forts and that they were spread across the area in this way, because the conventional wisdom was that these forts were the border between Rome and its enemies to the east, the Persian or Arab armies,” says Casana.

Other function
However, the distribution of the forts now discovered in images taken by spy satellites indicates that the forts had a completely different function. “Our results suggest that the forts functioned less as a border wall intended to prevent incursions and more to facilitate the movement of people, goods and military assets between east and west.” In that scenario, the forts did not form a wall, but rather a road or route through the Middle East.

Poidebard’s bias
According to the researchers, it can be explained that Poidebard came to a different conclusion a century ago. Poidebard said in 1934 that he flew his plane over areas in which he expected to discover forts. Expecting that forts would be found on the eastern border of the Roman Empire, he explored that area and – as expected – found forts. And that subsequently confirmed his idea of ​​a fortified eastern border. But had he looked further, as researchers were now able to do thanks to the spy satellites, he would probably have come to different conclusions.

Follow-up research
More research is needed to draw definitive conclusions about the function of these forts. Dating it is crucial, but difficult. Not only because of the unrest in the region, but also because it has proven difficult to collect sufficient datable material from such forts. And even if sufficient datable material is available, it is usually difficult to prove that it really came from the people who built the fort and were the first to inhabit it. “These materials may then come from subsequent use or reuse of the site, rather than from the phase in which it was built and used for military purposes,” the researchers write.

On the left you see some Roman forts on images from spy satellites. Image: J.Casana et al.; CORONA imagery courtesy US Geological Survey. And at the top right you see the forts that Poidebard discovered (and hinted at some kind of border guard). Bottom right the forts that Casana and colleagues documented. Image: J.Casana et al., created with ArcGIS Pro version 3.0.

On-site investigation
In short: for now we seem to have to make do with what the spy satellites tell us. However, the researchers certainly recommend that – as soon as the geopolitical situation allows – they should travel to the remains of the forts and conduct further research. Some haste is required. “Many of the Roman forts we documented in this study have already been destroyed by recent urban or agricultural development and countless others are extremely threatened.”

At the same time, however, the research also offers hope. “Our study shows that even in the well-explored northern part of the Fertile Crescent, important archaeological discoveries can be made using historical aerial and satellite images,” Casana said. And as more historical images become available or released (as in the case of spy data kept secret for decades), there is more and more for archaeologists to discover. Not only in the Middle East, but also beyond, the researchers emphasize.