Henry VII. in the last struggle before his death had clearly and correctly perceived that the key to the situation was in [Sidenote: Struggle in Tuscany.] Tuscany, that if the Ghibelline cause could triumph in that province the overthrow of the Guelfs might be confidently expected. And not long after his death the desired state of things seemed not unlikely to be realised. One of the most famous adventurers of the age, Castruccio Castracani, who had risen to prominence by his military ability, made himself lord of Lucca and there became a formidable neighbour to Florence. In 1325 he reduced the intermediate town of Pistoia, and defeated the Florentine forces at Altopascio. So terrified were the Florentines that they resolved to sacrifice their independence as the price of safety and the victory of their party. They offered the lordship of the city to Robert of Naples, who accepted it for his only son, Charles of Calabria. The progress of Castruccio was checked, and the appearance of Neapolitan forces in Tuscany impelled the Ghibelline leaders to call in the assistance of Lewis of Bavaria (_vide_ p. 104). Lewis [Sidenote: Lewis the Bavarian in Italy.] entered Italy in 1327, but his coming brought little real gain to his allies. In Milan he imprisoned his host, Galeazzo Visconti, and restored to the citizens a mockery of republican independence. Pisa, in spite of her Ghibelline traditions, stood a month’s siege before she would open her gates to a prince who might hand her over as a reward to his chief supporter Castruccio Castracani. No attempt was made to attack the Duke of Calabria in Florence, and Lewis hurried on to Rome. There he was crowned emperor. John XXII. was deposed as a heretic, and an Antipope was elected. Castruccio was formally created Duke of Lucca, Pistoia, and Volterra. But the news came that the Florentines had captured Pistoia by stratagem, and Castruccio had to hurry north for the defence of his duchy. He was indignant that Lewis had given the lordship of Pisa to the empress, and in defiance of imperial authority he took measures to secure his own rule in the city. From Pisa he advanced to a successful siege of Pistoia, but he died almost immediately after (September 3, 1328) of a fever contracted in the trenches.