The Pope, it seems, wished, at whatever price, to exterminate the Visconti.
He thundered this year against Barnabo with a terrible bull, in which he published a crusade against him.

Barnabo, to whom, with all his faults, the praise of courage cannot be denied, brought down his troops from the Po, in order to ravage Mantua, and to make himself master of that city.
Galeazzo, his brother, less warlike, thought of employing negotiation for appeasing the storm; and he invited Petrarch to Pavia, whither our poet arrived in 1368.

He attempted to procure a peace for the Visconti, but was not successful.
It was not, however, solely to treat for a peace with his enemies that Galeazzo drew our poet to his court.

He was glad that he should be present at the marriage of his daughter Violante with Lionel, Duke of Clarence, son of Edward III.

of England.