Adelbold
Adelbold (died 208) was, according to 19th-century historians, the second Duke of Frisia, and is now considered a fictional ruler of Frisia.
19th century biography
Adelbold, the second duke of Frisia, a son of Ascon, was a very unruly, warlike man, who kept himself busy with creating trouble between his neighbours and starting wars. He created battle schools, where Frisians boys of 15 years and older were educated in weaponry, and he sent his bastard brother Titus Bojocalis with auxiliary troops in the army of Emperor Marcus Aurelius against the Vandals. A group of 1500 Vandals went west to the borders of Denmark, which was at the time larger than it is now, but were driven away, after which they went south over Elbe and Weser towards Frisia. They had already reached the Eem when the Frisians appeared with all their power to prevent the enemy crossing the river. When both armies faced each other across the river, Titus Bojocalis together with eighthundred men crossed the Eem higher up the river and unexpectedly attacked the enemy, killing many of them and driving the remainder into the river. About four hundred of them crossed it swimming, but Adelbold killed most of them.
Adelbold, who contracted a debilitating disease after this victory, proposed the Frisians to appoint Titus as commander-in-chief in his stead. And so it came to be that Titus was elected Duke of the Frisians in 187. Shortly after he was thus promoted, Adelbold again regained his good health. Titus wanted to hand him the government back, but Adelbold, who together with his disease seemed to have lost his warriorlike character, rejected the offer and continued the rest of his life in quiet. He died in 208.
References
This article incorporates text translated from the article "Adelbold" in the Biographisch woordenboek der Nederlanden, a publication now in the public domain.