Still, there was more than chance in these disasters of the French in Italy. They had quite miscalculated the strength of their enemies, amongst whom was now the famous general, Charles de Bourbon, late Constable of France. The young French King, at a time when Spain, England, and Italy were all against him, had most unwisely deprived Bourbon of the whole of his vast estates by means of a legal quibble; and his greatest subject, driven to desperation by this ungrateful treatment, had passed over to the service of Charles V., and was now in command of the Spanish army. It was he who urged the immediate pursuit of the French when Bonnivet, discouraged by ill success and sickness in his camp, retreated from his strong position at Biagrasso. He made one blunder after another, for now that it was too late he sent a messenger to raise a levy of six thousand Swiss to join him by way of Ivria. According to his usual gallant custom, as the army retired with forced marches towards the Alps, Bayard took command of the rear-guard, and as the Spaniards followed day by day he bore all the brunt of the constant skirmishing which took place. It was a most perilous office, for the enemy was well provided with artillery, and when the Good Knight made a gallant charge with his company and drove back the men-at-arms, he would be attacked by a shower of stones from the arquebusiers. He seemed to bear a charmed life, though ever in the post of danger, for others were wounded or killed while he escaped unhurt until a certain fatal day when the retreating French army had reached the valley of the Sesia beyond Novara. Here it was that Bonnivet saw his expected troop of Swiss allies on the opposite bank of the river, and at once sent word to them to cross over and join him. But what was his dismay when the Swiss captains replied that the King of France had not paid them or kept his word, and they had come to fetch away their comrades who were in the French army. Worse still, when this became known, all the Swiss mercenaries in his camp rose in open rebellion against Bonnivet, and lost no time in crossing the river, overjoyed to leave a losing cause and go back to their homes with so good an excuse.