I did some years ago come across a few sites regarding their wars .. but I cant find them now.
On one of the links I've posted it says
Under Redbad, the tide turned in favour of the Franks: in 690 the Franks were victorious in the battle of Dorestad under the Austrasian mayor of the palace, Pepin of Herstal.[8] Though not all the consequences of this battle are clear, Dorestad became Frankish again, as did the castles of Utrecht and Vechten (nl). It is presumed that the influence of the Franks now reached from south of the Oude Rijn to the coast, but this is not entirely clear because the influence of the Frisians over the central river area was not entirely lost. In any case there was a Catholic Church mission to pagan Frisia with a monastery and episcopal see in Utrecht from 695, founded for Willibrord,[9][10][11] and a marriage was arranged between Grimoald the Younger the oldest son of Pepin, and Thiadsvind, the daughter of Redbad, in 711.[5](p794)
The Redad father of Thiadsvind, .https://en.wikipedia.org/wiki/Redbad,_King_of_the_Frisians
I'm not sure if this is in her profile or not or in Redbad's But I thought it should be.
I read Radboud of Utrecht was the son of Grimoald the Younger and Thiadsvind, van Friesland
https://en.wikipedia.org/wiki/Radboud_of_Utrecht .
Saint Radbod (or Radboud) (before 850 – 917) was bishop of Utrecht from 900 to 917.
He was a descendant of the last King of the Frisians. He spent his youth with his uncle Gunther, Archbishop of Cologne. After that, he served at the court of Charles the Bald.
When he was appointed as bishop of Utrecht in 900, the city was in ruins after a number of Norman raids. Like his predecessors, he was seated instead at Deventer.
He died in Ootmarsum in 917. His feast day is 29 November.
In the city of Nijmegen, the Netherlands, a university and a hospital are named after him: Radboud University Nijmegen and University Medical Center St Radboud, the latter being a part of the medical faculty of the university.
source of "Radbod, ruler of the Frisians"
In Richard Wagner's Lohengrin a certain "Radbod, ruler of the Frisians" is mentioned as Ortrud's father. It is possible that Wagner was thinking of the historical Radbod, although he died more than 150 years before the birth of Henry the Fowler, another character in the opera, who could not, therefore, be contemporary of Radbod's daughter.
In Harry Harrison's The Hammer and the Cross series of novels, Radbod becomes the founder of "the Way", an organized pagan cult, created to combat the efforts of Christian missionaries.
Black metal band Ophidian Forest recorded a concept album Redbad[8] in 2007.
Dutch folk metal band 'Heidevolk' recorded a song 'Koning Radboud' (King Redbad) on their 2008 album 'Walhalla Wacht' singing about the legend of Wulfram and Redbad.
I just find that very interesting
In 2015 the Frisian Folk-Metal band Baldrs Draumar[9] released a full album on the life and deeds of king Redbad called Aldgillessoan.[10] It is based on the book Rêdbâd, Kronyk fan in Kening[11] (Chronicles of a King) by Willem Schoorstra
