The duke Frederick, Henry's most devoted adherent, expired, in 1105, at the moment when his assistance was most needed; he left two sons, minors, Frederick and Conrad, and Prince Henry gained Swabia by wedding Frederick's widow, his own sister, to Leopold, Margrave of Austria, who united with Bohemia in favor of his cause. Wratislaw, the emperor's ally, was dead. His son, Brzetislaw II., was assassinated by the Wrssowez, who, notwithstanding the endeavors of Borzivoi II., Wratislaw's brother, and of the brave Wiprecht von Groitsch, succeeded in placing a relation, named Suatopluk, a friend of Prince Henry, on the throne of Bohemia.
The touching appeals of the emperor to his son being disregarded, he put himself at the head of his troops and marched against him. The cities remained faithful to their allegiance, and closed their gates against the rebellious prince, with the exception of Nuremberg, which was betrayed to him by the Jews, and almost entirely destroyed. Both armies met not far from Ratisbon, and the emperor, discovering that he was betrayed by his own followers, fled, perhaps too hastily, in the sorrow of his heart. He had still numerous adherents in the Rhine country, and his son, finding force unavailing, attempted by cunning to oblige him voluntarily to abdicate the throne, and proposed a conference at Coblentz. The emperor came; but struck to the heart at the sight of his ungrateful child, flung himself at his feet, exclaiming, "My son, my son, if I am to be punished by God for my sins, at least stain not thine honor, for it is unseemly in a son to sit in judgment over his father's sins." The prince, with assumed remorse, entreated his forgiveness, and, under pretense of accompanying him to the diet at Mayence, found means to separate him from his attendants, and to shut him up at Bingen, where he was required by the archbishops of Mayence and of Cologne, and the bishop of Worms, to give up the crown jewels.