[Sidenote: Election of Lothair II., 1125.]
In August 1125 the German magnates met together at Mainz to chose their new king. The antagonism of the nations was so fierce that, while Saxons and Bavarians encamped on the right bank of the Rhine, Swabians and Franks took up their quarters on the opposite side of the stream. A committee of forty princes, ten chosen from each of the four nations, was set up to conduct the preliminary negotiations, and if possible, to agree upon a candidate. Frederick of Swabia, Lothair of Saxony, and Leopold of Austria were all proposed as candidates. The craft of Adalbert of Mainz, as ever the foe of Henry V. and his house, prevented the election of the Staufer, by representing to the princes that Frederick’s choice would be interpreted as a recognition of an hereditary claim. For the first time since the election of Conrad II., the magnates had a free hand, and they could not resist the temptation to use it. Adalbert isolated Frederick by breaking up his new alliance with the Guelfs. Conrad of Franconia was away on Crusade. The alliance of Saxons and Bavarians, backed up by the skill of Adalbert, the zeal of the Papalists and the enthusiasm of the Rhineland, led to the election of Lothair.
[Sidenote: The reign of Lothair II., 1125–1138.]
Lothair II. reigned from 1125 to 1138. He was already sixty years old, at his accession, but he ruled with energy and vigour. By marrying his only daughter, Gertrude, to Henry the Proud, son of Duke Henry the Black, he united his fortunes with those of the house of Guelf, and prepared the way for that union of Saxony and Bavaria which had long been the Guelfs’ dream. [Sidenote: The Hohenstaufen subdued.] In these days the struggle of the rival families of Welf and Weiblingen, of Guelf and Ghibelline, first brought out the famous antagonism that in later times was extended over the Alps, and grew from a strife of hostile houses to a warfare of contending principles, and finally degenerated into the most meaningless faction fight that history has ever witnessed.
Lothair deprived Frederick of Swabia of part of the Salian lands inherited from Henry V. This was the signal of war between Swabian and Saxon, Weiblingen and Welf. In 1127 Conrad, the younger Hohenstaufen brother, was set up as anti-king, and in 1128 crossed the Alps in quest of the imperial crown and the heritage of the Countess Matilda. Milan welcomed him, and crowned him with the Iron Crown. But the Pope, Honorius II., excommunicated him, and he could make no way south of the Apennines. Meanwhile King Lothair and his son-in-law, Henry the Proud, took possession of the Rhenish towns that were the Hohenstaufen strongholds, and devastated Swabia with fire and sword. In 1134 Frederick gave up the contest, and next year Conrad also made his submission. Lothair showed politic magnanimity and left them their hereditary possessions.