By contrast with the vagueness of our knowledge of Pedro’s movements, those of de Montfort are known in detail. The crusading leader lay at Fanjeaux with a small force including thirty knights. Then as now, the early summer saw the high-water mark of the French energy, and by September the greater part of the forty-day Crusaders of that year had turned homeward. Although we know (from the interception of a private letter of Pedro’s) that de Montfort had some sort of intelligence service at work, nevertheless, his information seems to have been defective, so that he was surprised by Pedro’s move, perhaps because of its speed. When word came that the Aragonese was in Languedoc in arms, de Montfort at once sent his wife, the Countess Alice, to overtake certain temporary Crusaders who had just started homeward and, if possible, persuade them to return. The energetic countess made such haste that she gathered up at Carcassonne several hundred of the departing Crusaders, including the Viscount of Corbeil and that William des Barres who had commanded a “battle” (i.e., unit) under Cœur de Lion in the Third Crusade, including the bloody repulse of Saladin at Arsouf twenty-two years before. Even when these reinforcements had come in, de Montfort’s mobile force was small. He had about two hundred and sixty knights, and six hundred “sergeants,” that is cavalrymen heavily armed like knights but not of noble blood. King Pedro and the southern lords were known to be in great force. Most mediæval commanders, when gravely inferior in numbers, were accustomed to decline battle from behind walls, but Simon was an extraordinary man, and, moreover, he was driven by political necessity. Only the terror of his name made it possible for his small forces to hold down his thousands of unwilling southern subjects. To lose a strong place like the Castle of Muret might prove fatal to his prestige and be the signal for a general insurrection. Furthermore, he had not only boundless faith in his cause, but also a hearty contempt for the King of Aragon as an opponent. He knew that the Aragonese and the Languedocians were not accustomed to acting together, and would therefore have difficulty in deploying for action, especially if suddenly attacked. He therefore decided to take the field.