Chauci
The Chauci was a populous Germanic tribe inhabiting the extreme northwestern shore of Germany during Roman times - basically the stretch of coast between Frisia in the west to the Elbe estuary in the east. By the end of the 3rd century CE, they had merged with the Saxons : whether this conjunction was amicable or forced is not clear.
This article incorporates some information taken from http://www.hostkingdom.net/ with permission.