The young king of
East Francia,
Louis the Child, appointed
Gebhard to be the duke of Lotharingia in 903. His title was recorded in contemporary Latin as
dux regni quod a multis Hlotharii dicitur: "duke of the kingdom that many call Lothair's". He died in 910 fighting
Hungarian invaders. When non-Carolingian
Conrad I of Germany was elected king of
East Francia in 911, Lotharingian nobles under the new duke
Reginar voted to attach their duchy to West Francia, still ruled by the Carolingian dynasty. In 915,
Charles the Simple rewarded him by granting him the title of
margrave. Reginar was succeeded by his son
Gilbert who used the title
dux Lotharingiae: "duke of Lotharingia". When the West Franks deposed Charles in 922, he remained king in Lotharingia, from where he attempted to reconquer his kingdom in 923. He was captured and imprisoned by
Heribert II of Vermandois until his death in 929. In 923, king
Henry the Fowler of
East Francia used this opportunity and invaded Lotharingia (including
Alsace). In 925, Lotharingians under Gilbert elected Henry the Fowler to be their king. In 930, Gilbert's loyalty was rewarded and he received the prestigious hand of Henry's daughter
Gerberga in marriage. On Henry's death in 936, Gilbert rebelled and tried to swap Lotharingian allegiance to the West Franks, since their king
Rudolph was weak and would interfere less in local affairs. In 939, Henry's son and successor,
Otto I, Holy Roman Emperor, invaded Lotharingia, and at the
Battle of Andernach defeated Gilbert, who drowned trying to flee across the Rhine. The dukes of Lotharingia were thereafter royal appointees.
Henry I, Duke of Bavaria was duke for two years, followed in 941 by duke
Otto, who, in 944, was followed by
Conrad. Lotharingia was turned into a junior
stem duchy whose dukes had a vote in royal elections. While the other stem duchies had tribal or historic identities, Lotharingia's identity was solely political. King
Louis IV of West Francia tried to maintain a claim to Lotharingia by marrying Gilbert's widow and Otto's sister Gerberga. In his turn, Otto I accepted homage from West Francia's
Hugh the Great and
Herbert II, Count of Vermandois at
Attigny in 942. The weak Louis IV had no choice but to agree to Otto's continued suzerainty over Lotharingia. In 944, West Francia invaded Lotharingia, but retreated after Otto I responded with mobilization of a large army under
Herman I, Duke of Swabia. In 953, Duke Conrad rebelled against Otto I, and was removed from power and replaced by Otto's brother
Bruno the Great, who finally pacified Lotharingia. ==Partition of Lotharingia (959-965)==