Gudfred was the Danish king murdered in 810 before Charlemagne could confront him. A member of Gudfred’s own retinue killed him as Charlemagne prepared to respond to Danish aggression.
Gudfred had become alarmed by Charlemagne’s conquest of Saxony and the expansion of Frankish power toward the Elbe. In 804, Charlemagne transferred former Saxon territory north of the Elbe to his Obotrite allies, bringing the Frankish sphere close to Denmark. Gudfred responded by attacking the Obotrites and forcing several Slavic groups to pay tribute.
In 810, Gudfred raided Frisia, a wealthy coastal region of Charlemagne’s empire, and reportedly boasted that he would meet the Frankish ruler in open battle. Charlemagne began mobilizing, but the confrontation never occurred because Gudfred was assassinated by one of his followers.
The successor was Gudfred’s relative Hemming, who quickly sought peace with the Franks. That diplomacy led to the Treaty of Heiligen in 811. Sigfred and Hemming are common distractors: Sigfred was associated with the Danish succession, while Hemming followed Gudfred rather than being the king killed in 810.