Otto I (November 23, 912 - May 7, 973), also known as Otto the Great, was German king from 936 and emperor of the Holy Roman Empire from 962 until his death in 973.
Otto was born on November 23, 912 as the oldest son of Henry the Fowler and Matilda of Ringelheim. He inherited the Duchy of Saxony and the kingship of the Germans upon his father's death in 936. He also inherited his father's aggressiveness and continued the eastern expansion at the expense of the aristocracy. Through strategic marriages and personal appointments, Otto installed members of his family in the kingdom's most important duchies. This reduced the various dukes, who had previously been co-equals ith the king, to royal subjects under his authority. Otto transformed the Roman Catholic Church in Germany to strengthen the royal office and subjected its clergy to its personal control.
Magyar and Slavic resistance grew accordingly and threatened to turn the tide against him. He needed a larger army, but he knew that he could not rely on his vassal magnates to the west. Then, suddenly, his lucky day arrived. An enormous silver lode was discovered near Goslar in the Harz Mountains, in the heart of Otto's Saxon duchy, and he became all at once the wealthiest man in northern Europe. Mercenary knights and would-be vassals flocked to him, and with these forces, he was able to inflict a crushing defeat on the Magyars in 955 at the Battle of Lechfeld, thus ending the Hungarian invasions of Western Europe. The victory against the pagan Magyars earned him a reputation as a savior of Christendom and secured his hold over the kingdom. He quickly brought some of the rebellious duchies to his west to heel and replaced the dukes in power there with several of his sons.
Otto's support of the German Church led to the German Church's support of him. Court-directed missionary campaigns scoured the countryside for the rest of Otto's long reign. His last grand campaign was his effort to gain control of Italy. He succeeded in 961, when he invaded the peninsula at the request of the Pope, who wanted Otto's help against a local political rival. Early in 962, the Pope gave Otto the reward he had promised him as an enticement to march southward: the imperial title. Otto believed that as emperor, he controlled the papacy just as he controlled the Church within Germany. Reigning from Rome, Otto sought to improve relations with the Byzantine Empire and the Papacy. He finally returned to Germany in August 972 and died on May 7, 973, the following spring.
Otto married first to Eadgyth in 930. She died in 946.
Otto married second to Adelaide of Italy in 951.