Lothair was entirely untrustworthy and quite unable to maintain either the unity or the dignity of the empire of Charlemagne. See "Annales Fuldenses"; Nithard, "Historiarum Libri," both in the _Monumenta Germaniae historica. Scriptores, Bände_ i. and ii. (Hanover and Berlin, 1826 fol.); E. Mühlbacher, _Die Regesten des Kaiserreichs unter den Karolingern_ (Innsbruck, 1881); E. Dümmler, _Geschichte des ostfränkischen Reichs_ (Leipzig, 1887-1888); B. Simson, _Jahrbücher des deutschen Reiches unter Ludwig dem Frommen_ (Leipzig, 1874-1876). LOTHAIR II. or III. (c. 1070-1137), surnamed the "Saxon," Roman emperor, son of Gebhard, count of Supplinburg, belonged to a family possessing extensive lands around Helmstadt in Saxony, to which he succeeded on his father's death in 1075. Gebhard had been a leading opponent of the emperor Henry IV. in Saxony, and his son, taking the same attitude, assisted Egbert II., margrave of Meissen, in the rising of 1088. The position and influence of Lothair in Saxony, already considerable, was increased when in 1100 he married Richenza, daughter of Henry, count of Nordheim, who became an heiress on her father's death in 1101, and inherited other estates when her brother Otto died childless in 1116. Having assisted the German king, Henry V., against his father in 1104, Lothair was appointed duke of Saxony by Henry, when Duke Magnus, the last of the Billungs, died in 1106. His first care was to establish his authority over some districts east of the Elbe; and quickly making himself independent of the king, he stood forth as the representative of the Saxon race. This attitude brought him into collision with Henry V., to whom, however, he was forced to submit after an unsuccessful rising in 1112. A second rising was caused when, on the death of Ulrich II., count of Weimar and Orlamünde, without issue in 1112, Henry seized these counties as vacant fiefs of the empire, while Lothair supported the claim of Siegfried, count of Ballenstädt, whose mother was a relative of Ulrich. The rebels were defeated, and Siegfried was killed at Warnstädt in 1113, but his son secured possession of the disputed counties. After the defeat by Lothair of Henry's forces at Welfesholz on the 11th of February 1115, events called Henry to Italy; and Lothair appears to have been undisturbed in Saxony until 1123, when the death of Henry II., margrave of Meissen and Lusatia raised a dispute as to the right of appointment to the vacant margraviates. A struggle ensued, in which victory remained with the duke. The Saxony policy of Lothair during these years had been to make himself independent, and to extend his authority; to this end he allied himself with the papal party, and easily revived the traditional hostility of the Saxons to the Franconian emperors.