– DIEZ –

Lahngau was a region of Konradiner control from at least the middle of the ninth century. A division between upper and lower sectors had long existed; but as the Konradiner family began to flourish and proliferate, different forms of division were made to accommodate family members. The lower sector of Lahngau apparently was far less affected by divisions than the upper sector. Lower Lahngau came to Konrad Kurzbold, senior member of the Eberhardine branch of the Konradiner. He first emerges in 907 and is especially noted for founding the collegiate church of St. George in Limburg on the Lahn. At his death in 948 the county passed to his nephew Eberhard (III), senior member of the junior Eberhardine line, who died in 966.

Comital boundary: No further count emerges until Gerlach in 993, and it has been doubted that Gerlach’s county was based on the lower sector. What can be established is that Gerlach was prominent among those who took advantage of Otto of Hammerstein’s forfeitures under Emperor Henry II. At the time in question he documents deep in territory that would eventually pass to Otto’s Luxembourg heirs. If prior to Otto’s forfeitures he still documents for places slightly further up the valley than Lower Lahngau should extend, this may be because the boundaries are understood on the basis of deaconries that existed after 1024, when Konrad II came to the throne and restored Otto to prominence. As Otto’s enemy, Gerlach could expect punishment from the new monarch, and it is likely that the eastern boundary of his county was pushed westward in regions north of the Lahn. Discontinuity of the north-south line of deaconry boundaries, where the Lahn itself forms a boundary for several kilometers, supports this conclusion.

Later counts of Lower Lahngau definitely appear to descend from Gerlach. For example, we must explain how a variety of rights in this region passed to the middle-Rhenish counts of Leiningen. If Count Godebold of Lower Lahngau was count in the region of Villmar in 1053, and if Count Frederick I of Leiningen was advocate of the church of Villmar in the later twelfth century, it is not unlikely that Frederick descended from Godebold. It is for this reason, presumably, that the name Gerlach begins to appear among Leiningen ascendants in a son of Count Emicho of Flonheim, who must have married Godebold’s daughter.

General reconstruction: Gerlach being accepted as the first of this dynasty, a Count Erkanbold should be accepted as his successor. Erkanbold held the burgravate of Mainz, as did Count Godebold, who was succeeded in Lower Lahngau by Imbricho I, the first to bear the Diez cognomen. Other members of this family should include a Burgrave Gerlach of Mainz documented in 1047, from whom the lords (sometimes counts) of Isenburg should descend. A Gerlach who represented imperial interests in Weilburg in 1062 may be the documented but anonymous brother of Imbricho I. The Diez family remains difficult to reconstruct for some generations. The simplest solution finds Henry I (fl. 1101-7) and his brother Gerhard as sons of Imbricho I, and Henry as father of Imbricho II (fl. 1133), who married a daughter of Rupert of Laurenburg. From that point forward the dynasty is much better documented.

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