The Great (Barbarian) Conspiracy in Britain AD 367: Was it a real event?

[guy]

A previous post discussed the Great Conspiracy in AD 367 (see below), which involved a nearly simultaneous attack on Britain by invading barbarian tribes. But did such an event occur, or was it merely a fabrication by Ammianus Marcellinus writing in distant Antioch?

The background story:

The Great Conspiracy of AD 367 was a significant coordinated attack on Roman Britain by various groups, including the Picts, Scots, Attacotti, Saxons, and Franks. The Roman military presence in Britain had weakened, allowing these groups to exploit the situation by launching simultaneous invasions across different regions.

The attacks overwhelmed Roman defenses, leading to the sacking of cities and widespread chaos. Roman officials, such as Nectaridus, the Count of the Coastal Region, were killed, while others were besieged or captured. The Roman intelligence network also collapsed, as local agents betrayed their paymasters, making the attacks unexpected and devastating.

In response, Emperor Valentinian I sent Count Theodosius [father of the future Emperor Theodosius the Great] to restore order. Theodosius successfully reclaimed lost territory, rebuilt fortifications, and reestablished Roman control over Britain. His efforts stabilized the province, but the Great Conspiracy revealed the vulnerabilities of Roman Britain in its later years.

 

 

Caldrail had presented a post about the little-known Bokerley Dyke with a video suggesting a possible role during the Great Conspiracy.

 

 

During the Roman period, the dyke was breached by a Roman road known as Ackling Dyke, which connected Old Sarum and Badbury Rings. However, in the 4th century, the dyke was remodeled and reinstated, possibly as a defensive structure against invasions during the Great Conspiracy of AD 367. Excavations have revealed that the Roman road was blocked, and a coin of Emperor Valens suggests this activity occurred shortly after AD 364.

 

One coin does not constitute substantial evidence; nevertheless, it does suggest that the dyke had a role in the conspiracy.

 

The Great Conspiracy of AD 367 is mainly documented by Ammianus Marcellinus, a 4th-century Roman historian, who described it as a barbarica conspiratio ("barbarian conspiracy"). His account details how various groups—the Picts, Scots, Attacotti, Saxons, and Franks—coordinated attacks on Roman Britain, overwhelming defenses, and causing widespread destruction. Marcellinus wrote his accounts about The Great Conspiracy while working in Antioch (modern-day Antakya, Turkey), about 3000 km (1800 miles) from the events.

Archaeological evidence supports the historical narrative by showing signs of reinforced fortifications and Roman military movements in response to the crisis. Excavations at sites like Bokerley Dyke suggest that defensive measures were implemented during this period, possibly linked to the Roman response. Furthermore, Roman coins from the reign of Emperor Valentinian I have been discovered in locations associated with military rebuilding efforts, indicating a concerted effort to restore order.

While Ammianus' account is the most detailed, some scholars question its accuracy, noting that he wrote from Antioch and may have relied on second-hand information. Despite this, the combination of written records and archaeological findings provides evidence that the Great Conspiracy was a real and significant event in Roman Britain's history.

 

Here is an excellent video on the conspiracy:

 

 

 

Edited yesterday at 09:31 PM by guy