One of the most formidable Milanese archbishops was Ariberto of Intimiano, who held the position from 1018 to 1045, and was one of the most powerful men in Northern Italy. Basically a military man, he fought in the name of the German Holy Roman Emperors, waging a successful military campaign for them against the city of Lodi, and later crossing the Alps to battle the French Count Eudes II of Champagne.
While he was away on the French campaign, an insurrection broke out among a class of knights and lesser nobles called the “valvassori,” and spread across the Northern Italian region of Lombardy, of which Milan was a part. Ariberto led the regional efforts of his own class of senior nobles (“capitanei”) to restore order and the status quo, and appealed to Emperor Conrad II for help.
At this point, Conrad seems to have viewed Ariberto’s growing regional stature as a threat to his own power. Instead of helping Ariberto, in 1037 Conrad convened a diet in Pavia, where he put him on trial. Ariberto proudly refused to defend himself, and was arrested and imprisoned—but escaped back to Milan.
Conrad marched on Milan. The Milanese put aside their earlier differences to close ranks in the face of this common threat, and the emperor was repelled.
Conrad’s next tactic was to officially depose Ariberto and name a new archbishop. (Naming the Archbishop of Milan was the Holy Roman Emperor’s legal right.) The Milanese responded by destroying the new appointee’s houses.
Meanwhile, Ariberto tried a scheme of his own, offering his former opponent Eudes II of Champagne the throne of Northern Italy in exchange for a protective alliance. Unfortunately for Ariberto, Eudes died before his envoys could reach him.
When the Emperor learned of this move, he forced Pope Benedict IX, a corrupted figure who was emblematic of the depths to which the papacy had sunk, to excommunicate Ariberto in 1038. This action also failed to unseat Ariberto.
Conrad again tried military means in 1039, and succeeded in getting an army of his allies to surround Milan. But Conrad abruptly died, and the siege was lifted when word of his demise reached the assembled forces.
The following spring, Ariberto went north to swear the customary oaths of loyalty and fealty to Conrad’s son and successor, Henry III. While he was away, a nobleman named Lanzone led an uprising of Milanese commoners against the nobility, which drove Ariberto and his nobles into exile, until a peace was finally concluded in 1044. Ariberto died shortly thereafter.