She increased the animosity against herself by going to Lorraine to claim her dead husband's lands in Verdun. Godfrey the Hunchback, however, had willed it to his nephew, Godfrey of Bouillon. Godfrey was understandably opposed to this, and also argued that she should not have the estates that had been given by Godfrey's father when he married Matilda's mother. The debate went before Bishop Theodoric of Verdun, who pleased himself and the pope by ruling in Matilda's favor. (Godfrey went on to became historically famous in other ways.)
Her first large-scale political event was providing military protection for Pope Gregory when he traveled north to meet with Holy Roman Emperor Henry IV during their conflict—as Margravaine of Tuscany and heir to Canossa she technically controlled all the passes across the Apennines. Henry decided to travel south, however, and meet Gregory on Henry's terms. Gregory had excommunicated Henry and placed Germany under Interdict (so no one in Germany could receive any Sacraments). German nobles had told Henry he had to submit to the pope within a year or be deposed.
Learning of Henry's approach, Matilda told Gregory to come to Castle Canossa for safety. There was no danger, however: it turns out that Henry was coming to do penance. At the end of January 1077, Henry stood outside the gates of Canossa, barefoot in the snow, for a few days to show his sincerity. He had his wife and son and some others with him. The pope finally forgave him.
Matilda likely had a significant role in the negotiations that followed, given her political position as well as her role as host at Canossa. She continued to make waves, fighting later with Henry. Her court became a center of art and culture in northern Italy, and she became known as la Gran Contessa. She encouraged scholars to publish their works. We have a psalter written at her request by Bishop Anselm of Lucca. Johannes of Mantua made a commentary in the Song of Songs. Several works were also dedicated to her, which she had copied and distributed.
As the years went by, she became mindful of the fact that she was the last heir to the House of Canossa. Her search for an heir led to a second marriage to a man 20 years younger. That didn't work out, but she thought of another option. I'll tell you about those tomorrow.