Through the activity of the Nadhirites the Arabian tribes were induced to join in the war. They found it more difficult, however, to induce their co-religionists, the Benu-Kuraiza, to take part. Kaab-Ibn-Assad, the governor of Kuraiza, at first would not receive the Nadhirite Hujej, who had desired his protection, because his tribe had made an alliance with Mahomet and the Moslems, and he was so guileless as to rely on Mahomet's word. Hujej managed to convince him of the danger which threatened the Jews, and to persuade him that the victory of so many allies over the less numerous Moslems was certain. The Benu-Kuraiza yielded to his arguments. Ten thousand of the allied troops took the field, and intended to surprise Medina. Mahomet, forewarned by a deserter, would not allow his army, which was inferior in numbers, to fight a pitched battle. He fortified Medina by surrounding it with a deep ditch and other defenses. The Arabs, accustomed to fight in single combat, vainly discharged their arrows against the fortifications. Mahomet succeeded finally in sowing the seeds of mutual distrust among the chief allies, viz., the Koraishites, the Ghatafan and the Jews. The "War of the Fosse" terminated favorably for Mahomet, and very unhappily for the Jews, upon whom the whole of his wrath now fell. On the day after the departure of the allies, Mahomet, with 3000 men, took the field against Kuraiza, announcing that he was thus obeying an express revelation. His next step was to arouse the enthusiasm of his followers in the cause of the war. "Let him that is obedient offer up his prayers in the neighborhood of Kuraiza," was the formula with which he exhorted them. The Jews, unable to resist in a battle, retired to their fortresses, which they put into a state of defense. Here they were besieged by Mahomet and his troops for twenty-five days (February-March, 627). Food then began to fail the besieged, and it became necessary to think of capitulation. They besought Mahomet to treat them as he had treated their brethren, the Nadhirites, viz., allow them to withdraw with their wives, their children, and a portion of their property. The vindictive prophet, however, refused their request, and demanded unconditional surrender.