In 1329, with the support of another uncle, Giovanni, he bought the title of imperial vicar of Milan from the emperor Louis IV for 60,000 (or 125,000) florins.

[citation needed] This maneuver drew the ire of Pope John XXII, who excommunicated Azzone, placed the city of Milan under interdict, and threatened an invasion by his French allies.

[5] In the August of the same year he allied with Theodore I, Marquess of Montferrat, against King Robert of Anjou, in order to capture his possessions in north-western Italy.

In 1332 he also conquered Bergamo and Pizzighettone, continuing in 1335 with Lodi, Crema and other Lombardy lands who had ceded themselves to the Papal States, as well as Vercelli and Cremona.

Azzone died 16 August 1339 of a gout attack,[a] and was buried in the church of San Gottardo, which he had commissioned some years before.