Castruccio had left as his deputy in Lucca, Pagolo Guinigi, who was held in high estimation, because of the people's love for the memory of his father.

Castruccio was received in great honour by Frederick, and many privileges were conferred upon him, and he was appointed the emperor's lieutenant in Tuscany.

At this time the Pisans were in great fear of Gaddo della Gherardesca, whom they had driven out of Pisa, and they had recourse for assistance to Frederick.

Frederick created Castruccio the lord of Pisa, and the Pisans, in dread of the Guelph party, and particularly of the Florentines, were constrained to accept him as their lord.
Frederick, having appointed a governor in Rome to watch his Italian affairs, returned to Germany.

All the Tuscan and Lombardian Ghibellines, who followed the imperial lead, had recourse to Castruccio for help and counsel, and all promised him the governorship of his country, if enabled to recover it with his assistance.