I've spent the past several years researching Charlemagne's Saxon War (circa 772 to 804 AD), with an eye to setting a novel in the middle of the war. I've found a lot to use, but there are a few unsettled questions; one of them is the identity of Widukind, who led the fight for a bit over a decade.
Google searches led to a lot of information . . . that just didn't seem right, so I rapidly turned to using them only to find source material, written during, or a generation or so after, the Saxon War. As a result, I've read (in translation) the biographies of Charlemagne written by Einhard and Notker the Stammerer (aka, in some sources, "Monk of St Gall"). I've also read the Royal Frankish Annals, which are more helpful for my purposes. Unfortunately, about all they say about Widukind's background is to call him "a duke of the Saxons."
This seems helpful, until you look at who else they called dukes. In at least one case, they were minimizing someone whose subjects called him King. In other cases, they seem to remember that Duke was derived from the Roman military title for a legion's commander, and apply the term to generals. Admittedly, in most cases, they seem to be talking about a high-ranking noble, as anyone familiar with British nobility would expect.
Is anyone aware of any other sources I should be reading?