The Frankish Conquest of Frisia and the Battle of the Boarn (734)
By the 8th century, Frisia stretches from the Belgian border to the Weser River in Germany, encompassing a vast coastal region inhabited by fiercely independent tribes. The Franks and the Frisians have long engaged in conflicts and skirmishes, with Frankish rulers seeking to impose their authority over the region.
In 734, Charles Martel launches a major invasion of Friesland, leading a Frankish army deep into Frisian territory. This campaign, part of a larger series of ongoing wars, aims to subjugate the Frisians and eliminate their remaining resistance to Frankish rule and Christianity.
The Battle of the Boarn (734)
Advancing along the River Boarn, the Frankish forces reach its mouth, where it once flowed into the Bordine estuary (or Middelsee)—a body of water that, over centuries, will silt up and be reclaimed for agriculture (10th–14th century).
Here, the Frisian king Poppo attempts to ambush the Frankish army by landing his warriors by boat, launching a surprise attack against Charles’s forces. However, despite their tactical maneuvering, the Frisians are decisively defeated, and King Poppo is slain in battle.
With this victory, the Franks gain control of the Frisian lands west of the Lauwers estuary, forcing the surviving Frisians into vassalage under Frankish rule. However, East Frisia (present-day northern Germany) remains outside Frankish control, with the tribes beyond the Weser continuing to resist Christianization and Frankish authority.
The Aftermath: Frankish Expansion and Frisian Submission
The Battle of the Boarn marks a turning point in the subjugation of Frisia. While Frankish rule is now firmly established in Western Frisia, the region remains culturally distinct, with lingering resistance to Christianization and Frankish governance. The surviving Frisians will continue to assert their independence, and future Frankish campaigns will be necessary to fully integrate them into the Carolingian realm.
With his victory in 734, Charles Martel further expands his dominion, reinforcing Frankish supremacy over northern Gaul and solidifying his legacy as the undisputed ruler of Francia.
