Archaeologists Discover Large Number of Ancient Roman Forts in Fertile Crescent

During a pioneering aerial survey of the Near East in the 1920s, the Jesuit French priest Father Antoine Poidebard recorded 116 fortified military buildings that traced the eastern frontier of the Roman Empire. Based on their distribution, Poidebard proposed that these forts represented a line of defense against incursions from the east. Using declassified images from the CORONA and HEXAGON spy satellite programs, archaeologists have now identified a further 396 ancient forts widely distributed across the northern Fertile Crescent, spanning from what is now western Syria to northwestern Iraq. The spatial distribution of the forts the authors have mapped no longer supports Poidebard’s central thesis that they constituted a broadly north-south line along the eastern boundary of the Roman Empire.

In the 1920s, at the beginning of the ‘age of aviation,’ Father Antoine Poidebard undertook one of the world’s first aerial archaeological surveys, using a biplane and a camera to document hundreds of ancient forts and other sites throughout what today is Syria, Iraq and Jordan.

Having piloted a biplane during the First World War, Poidebard later became a priest at Université Saint-Joseph in Beirut and joined the 39th Aviation Regiment of the French Levant forces, through which he began his expansive aerial survey of desert regions.

Although today Poidebard is remembered primarily for his technological innovation in using aerial photography as an archaeological survey tool, an achievement that also fascinated his contemporaries, the substance of his investigation was based on mapping Roman-period forts and defensive installations along the eastern periphery of the empire.

In his magisterial monograph, Poidebard presented hundreds of previously unknown forts and other sites over an area that stretches more than 1,000 km along the Roman frontier or limes.

Poidebard reported that the forts were constructed from north to south to establish an eastern boundary of the Roman Empire.

The new study reveals 396 previously undocumented Roman forts and reports that these forts were constructed from east to west.

“I was surprised to find that there were so many forts and that they were distributed in this way because the conventional wisdom was that these forts formed the border between Rome and its enemies in the east, Persia or Arab armies,” said Dartmouth College’s Professor Jesse Casana.

“While there’s been a lot of historical debate about this, it had been mostly assumed that this distribution was real, that Poidebard’s map showed that the forts were demarcating the border and served to prevent movement across it in some way.”

For the study Professor Casana and colleagues drew on declassified Cold-War era CORONA and HEXAGON spy satellite imagery from the 1960s and 1970s.

The researchers examined satellite imagery of approximately 300,000 km2 of the northern Fertile Cresent.

They mapped 4,500 known sites and then systematically documented every other site-like feature in each of the nearly 5 by 5 km survey grids, which resulted in the addition of 10,000 undiscovered sites to the database.

When the database was originally developed, they had created morphological categories based on the different features evident in the imagery.

One of the categories was Poidebard’s forts — distinctive squares measuring approximately 50 by 100 m.

The forts would have been large enough to accommodate soldiers, horses, and/or camels.

Based on the satellite imagery, some of the forts had lookout towers in the corners or sides.

They would have been made of stone and mud-brick or entirely of the latter, so eventually, these non-permanent structures would have melted into the ground.

While most of the forts that Poidebard documented were probably destroyed or obscured by agriculture, land use, or other activities between the 1920s and 1960s, the authors were able to find 38 of 116 of Poidebard’s forts, in addition to identifying 396 others.

Of those 396 forts, 290 were located in the study region and 106 were found in western Syria, in Jazireh.

According to the team, the newly-discovered forts are likely to be Roman in date.

They are most frequently square fortifications measuring 50-80 m per side, but the archaeologists also found numerous larger, more complex fortresses comprised of multiple buildings and larger enclosure walls up to 200 m per side.

“The most common form that we interpret as a probable fort is a classic square shape, typically 50-80 m per side,” the researchers said.

“These buildings are often isolated, far from other obvious archaeological features, and frequently located in marginal environments with little other evidence of ancient or modern settlement.”

“Our observations are pretty exciting and are just a fraction of what probably existed in the past,” Professor Casana concluded.

“But our analysis further supports that forts were likely used to support the movement of troops, supplies, and trade goods across the region.”

The team’s paper was published in the journal Antiquity.