Adalbert Atto was the first Count of Canossa and founder of that noble house which eventually was to play a determinant role in the political settling of Italy and the Investiture Controversy in the eleventh and twelfth centuries. Adalbert first appears in sources as a son of Sigifred of Lucca. He was originally a vassal of King Lothair II and a miles of Adelard, Bishop of Reggio. He rose to prominence rapidly by sheltering Queen Adelaide in his castle at Canossa after she fled from the castle of Garda, where Berengar II had imprisoned her. In 958, Adelaide made him a count sine re, that is, without an exclusive jurisdiction of right of inheritance. He did not appear again as a count in documents until December 961, during Berengar's ascendancy. On 20 April 962, he appeared as count of Reggio and Modena. These appointments were probably a further product of his support for Adelaide and her new husband, Otto I of Germany. With the queen, he negotiated a division of power with the bishop of Reggio whereby the bishop was confirmed as comes civitatis, count of the city, and Adalbert as comes comitatus, count of the county, where the county was said to begin three or four miles outside the city walls. He appears with a similar title, comes comitatus Mantuanensis, in Mantua in a letter of the abbess of Santa Giulia dated 10 June 977. In 984, Adalbert appears as a margrave. When Henry II, Duke of Bavaria, was acclaimed as king that year, he united Parma, Piacenza, Bergamo, Cremona, and Brescia to Adalbert's territories. However, Henry's usurpation of the throne was brief. Adalbert Atto built a monastery at Canossa in 961, dedicated to S. Apollonio in 971. He also built a monastery at Brescello. He and his family were all buried in S. Apollonio. Adalbert married the Supponid Hildegard and had three sons: Geoffrey; Tedald, who became respectively bishop and count of Brescia; and Rudolph, who predeceased him. He had a daughterPrangarda who married Manfred I of Susa.
