But Isabella had no sooner assumed the title of Queen of Castile, than she was called upon to maintain her pretensions in the field. With no experience but that of a country palace, with no training but that of a country cloister, she set herself to work to organize an army. On the 1st of May, 1474, five hundred horsemen represented the entire forces of the fair usurper. By the 19th of July she had collected over forty thousand men, had armed and equipped them ready for the field, and had sent them forward under the command of Ferdinand to the frontier. Although she was at the time in delicate health, she was constantly in the saddle, riding long distances from fortress to fortress, hurrying up recruits all day, dictating letters all night, giving her zealous personal attention to every detail of armory and equipment, showing from the first that quiet energy and that natural aptitude for command that ever so constantly distinguished her. That her levies were not victorious in no way daunted her determination. A second army was raised by her, within a few weeks after the first had melted away under Ferdinand; nor would she listen to any offers of negotiation, until the enemy had been driven out of Castile. In the conduct of the war of Granada, with time and money at her command, her preparations were upon a very different scale. The most skillful artificers were summoned from every part of Europe to assist in the work of supplying the army with the necessary material of war. Artillery, then almost unknown to the military art, was manufactured in Spain according to the best designs. Model cannon were imported, and the necessary ammunition collected from abroad. Sword-blades were forged at home. Not only a commissariat, but a field hospital--institutions till then unheard of in Spanish warfare--were organized and maintained under the personal supervision of the queen. The presence of a lady on the day of battle would, as a rule, as she rightly judged, have been rather a hinderance than a help; but she was very far from being a mere commissioner of supply. A first-rate horsewoman, she was constantly seen riding about the camp, encouraging, inspecting, directing; and in the last days of the siege of Granada, when the spirits of the troops had begun to flag, she appeared daily in complete armor, and showed herself upon more than one occasion in a post of danger on the field. The armies with which Gonsalvo de Cordova overran Calabria, and annihilated the French at Cerignola, were prepared and dispatched by Isabella; and if, in a subsequent campaign, the Great Captain was left without supplies or re-enforcements, it was that the queen was already sickening to her death, broken down and worn out by her constant and enormous exertions.