After Conrad's death Germany passed under the rule of one of the greatest of her sovereigns, Frederick I., called Barbarossa, nephew of the late king and son of Frederick, that duke of Swabia who had fought along with Conrad against Henry the Proud. Frederick himself had also been closely associated with Conrad, who advised the princes to choose his nephew as his successor. This was done, and the new king was crowned at Aix-la-Chapelle in March 1152. Allied through his mother to the Welfs of Bavaria, and anxious to put an end to the unrest which dominated Germany, especially to the strife between the families of Welf and Hohenstaufen, Frederick began his reign by promising to secure for Henry the Lion the duchy of Bavaria, and by appeasing Henry's uncle, Count Welf, by making him duke of Spoleto and margrave of Tuscany. But the new king had another, and perhaps a more potent, reason for wishing to see peace restored in Germany. For his adventurous and imaginative spirit Italy and the imperial title had an irresistible charm, and in 1154, two years after he had ascended the throne, he crossed the Alps, being crowned emperor at Rome in June 1155. After this event the best years of his life were spent in Italy, where, in his long and obstinate struggle with the Lombard cities and with Pope Alexander III., he chiefly acquired his fame. Although on the emperor's side this struggle was conducted mainly with German troops it falls properly under the history of Italy. In that country the record of this reign is a blood-stained page, while in the history of Germany, on the contrary, Frederick's name is associated with a peaceful and prosperous period. Bavaria and Saxony.