Key Facts
- Duration of siege
- 33 days
- Siege outcome
- Avar-Slav attack repulsed; city held
- Primary source
- Miracles of Saint Demetrius
- Siege technology used
- Siege engines deployed by attackers
- Significance in series
- Last and best-organized Avar attempt on Thessalonica
Strategic Narrative Overview
The siege began in 617 or 618 and lasted 33 days, making it the most sustained and organized assault the Avars had yet mounted against Thessalonica. The attackers employed siege engines in an attempt to breach or overcome the city's defenses. Despite the sophistication of the assault, the Byzantine garrison and population successfully resisted throughout the duration of the siege.
01 / The Origins
By the early 7th century, the Avar Khaganate and allied Slavic tribes (Sclaveni) had spread across much of the Balkans, pressing against Byzantine-held cities. Thessalonica, the empire's principal stronghold in the region, was a recurring target. The Avars sought to neutralize this fortified hub to consolidate control over the surrounding territory they and their Slavic clients had settled.
03 / The Outcome
The siege ultimately failed, and the Avar and Slavic forces withdrew without capturing the city. Thessalonica remained under Byzantine control. The failed assault marked the end of major Avar-led efforts to take the city. The events were subsequently recorded in the hagiographic collection known as the Miracles of Saint Demetrius, which attributed the city's salvation to its patron saint.
Belligerents & Mobilization Analysis
Side A
2 belligerents
Side B
1 belligerent
Kinetic Engagement Axis
Scroll horizontally to view full axis. Events plotted relatively.