In 1325, Castruccio, having taken possession of Pistoia, became so powerful that the Florentines, fearing his greatness, resolved, before he should get himself firmly seated in his new conquest, to attack him and withdraw it from his authority.  Of their citizens and friends they mustered an army amounting to 20,000 foot and 3,000 horse, and with this body encamped before Altopascio, with the intention of taking the place and thus preventing it from relieving Pistoia.  Being successful in the first part of their design, they marched toward Lucca, and laid the country waste in their progress; but from the little prudence and less integrity of their leader, Ramondo di Cardona, they made but small progress; for he, having observed them upon former occasions very prodigal of their liberty, placing it sometimes in the hands of a king, at others in those of a legate, or persons of even inferior quality, thought, if he could bring them into some difficulty, it might easily happen that they would make him their prince.  Nor did he fail frequently to mention these matters, and required to have that authority in the city which had been given him over the army, endeavoring to show that otherwise he could not enforce the obedience requisite to a leader.  As the Florentines did not consent to this, he wasted time, and allowed Castruccio to obtain the assistance which the Visconti and other tyrants of Lombardy had promised him, and thus become very strong.  Ramondo, having willfully let the opportunity of victory pass away, now found himself unable to escape; for Castruccio coming up with him at Altopascio, a great battle ensued in which many citizens were slain and taken prisoners, and among the former fell Ramondo, who received from fortune that reward of bad faith and mischievous counsels which he had richly deserved from the Florentines.  The injury they suffered from Castruccio, after the battle, in plunder, prisoners, destruction, and burning of property, is quite indescribable; for, without any opposition, during many months, he led his predatory forces wherever he thought proper, and it seemed sufficient to the Florentines if, after such a terrible event, they could save their city.

Still they were not so absolutely cast down as to prevent them from raising great sums of money, hiring troops, and sending to their friends for assistance; but all they could do was insufficient to restrain such a powerful enemy; so that they were obliged to offer the sovereignty to Charles duke of Calabria, son of King Robert, if they could induce him to come to their defense; for these princes, being accustomed to rule Florence, preferred her obedience to her friendship.  But Charles, being engaged in the wars of Sicily, and therefore unable to undertake the sovereignty of the city, sent in his stead Walter, by birth a Frenchman, and duke of Athens.  He, as viceroy, took possession of the city, and appointed the magistracies according to his own pleasure; but his mode of proceeding was quite correct, and so completely contrary to his real nature, that everyone respected him.