Bourbon watched the brilliant host as it deployed upon the plain, and as he followed the movements of the king, whose lofty stature and magnificent armour revealed him to all eyes, he thought that the hour of vengeance had come. On either side there was confident anticipation of victory. François made sure of overthrowing his enemies, and punishing the audacious rebel who had invaded his kingdom, while Bourbon felt equally certain of vengeance. No sooner had the king so imprudently quitted the park with his host, than Del Vasto abandoned the Castle of Mirabello, of which he had taken possession, and, hurrying after them with his three thousand Spanish fantassins, attacked the French rear. At the same time De Leyva issued from the gates of Pavia with the whole of the garrison and engaged with Chabot de Brion, who had been left to oppose him with a very inferior force. When drawn up for battle, the French army formed a very extended line, the right wing being commanded by the Marshal de Chabannes, and the left by the Duke d'Alençon. Between the right wing and the main body, with whom was the king, were the Black Bands, commanded by the Duke of Suffolk. On the left was a corps of ten thousand Swiss, commanded by Diesbach. The Imperial army likewise formed a long line, but was divided into a great number of squadrons all ready to act together, or separately, as circumstances might dictate. No sooner was his line formed than the fiery French king, who was all impatience for action, bade the trumpets sound, and called to his gendarmes to charge. Couching his long lance, and closely attended by Bonnivet and all his young nobles and esquires, François hurled himself against Castrioto, who, with his squadron of light horse drawn up in a close square, awaited his attack. The shock was terrific and irresistible. Down went horse and man before the French chivalry, and Castrioto was transfixed by the king's own lance. Their leader gone, the horsemen could not rally, but were quickly dispersed, while the victorious king, without pausing, turned his arms against Lannoy and his Neapolitans, almost as speedily routing them as he had done the horse of Castrioto. “Your majesty seems to have decided the battle with a blow,” remarked Bonnivet, as they stopped to breathe their horses, while the men-at-arms pursued the fugitives. “At last, I am Duke of Milan,” said François, laughing, and fully persuaded he had gained the victory. But he was speedily undeceived. Pescara had chosen this moment, when the squadrons of Castrioto and Lannoy were routed, to bring up his Basque arquebussiers. Advancing rapidly within a short distance of the French gendarmes, these unerring marksmen fired with deadly effect, retreating before their opponents, encumbered by their heavy armour, could touch them.