German king and Roman emperor, born Jesi, Ancona, Papal States, 26 December 1194; died Fiorentina, Apulia, Sicily, 13 December 1250.
He was the son of Henry II and Constance of Sicily.
Through the aid of Innocent III, Frederick overthrew Otto IV, emancipated the Church from undue royal influence, and vowed to undertake a crusade.
His son Henry was elected king and, entrusting the affairs of Germany to Archbishop Engelbert of Cologne, he returned to Italy and was crowned emperor, 1220.
Frederick made Italy the center of his power.
He controlled southern Italy and Sicily, though he had been forced to acknowledge the pope as his overlord in the latter.
His desire of reestablishing the imperial power in northern Italy was opposed by a league of the Italian cities and also by the Holy See, as it endangered the liberties of the Papal States.
His continued neglect to fulfill his vow led the newly-elected Gregory IX to excommunicate him, and thus precipitated a struggle.
Frederick, however, now proceeded to the Holy Land, crowned himself King of Jerusalem, and on his return forced the pope to absolve him.
He then resumed his north Italian policy, but was frustrated by the rebellion of his son Henry in Germany, whom he soon captured.
He promulgated at Mainz the famous Laws of the Empire, 1235, and having restored order in Germany returned to subdue the Lombards.
The Papal States were soon involved and matters were going badly for Gregory IX, when he died.
After the election of Innocent IV, Frederick was again excommunicated by the Council of Lyons; several pretenders appeared in Germany, but at the time of his death several years had elapsed without a decisive conflict.
New Catholic Dictionary