The Khalifa's plan of attack appears to have been complex and ingenious. It was, however, based on an extraordinary miscalculation of the power of modern weapons; with the exception of this cardinal error, it is not necessary to criticise it. He first ordered about 15,000 men, drawn chiefly from the army of Osman Sheikh-ed-Din and placed under the command of Osman Azrak, to deliver a frontal attack. He himself waited with an equal force near Surgham Hill to watch the result. If it succeeded, he would move forward with his bodyguard, the flower of the Arab army, and complete the victory. If it failed, there was yet another chance. The Dervishes who were first launched against the zeriba, although very brave men, were not by any means his best or most reliable troops. Their destruction might be a heavy loss, but it would not end the struggle. While the attack was proceeding, the valiant left, consisting of the rest of the army of Osman Sheikh-ed-Din, might move unnoticed to the northern flank and curve round on to the front of the zeriba held by the Egyptian brigade. Ali-Wad-Helu was meanwhile to march to the Kerreri Hills, and remain out of range and, if possible, out of sight among them. Should the frontal and flank attacks be unhappily repulsed, the 'enemies of God,' exulting in their easy victory over the faithful, would leave their strong place and march to the capture and sack of the city. Then, while they were yet dispersed on the plain, with no zeriba to protect them, the chosen warriors of the True Religion would abandon all concealment, and hasten in their thousands to the utter destruction of the accursed--the Khalifa with 15,000 falling upon them from behind Surgham; Ali-Wad-Helu and all that remained of Osman's army assailing them from Kerreri. Attacked at once from the north and south, and encompassed on every side, the infidels would abandon hope and order, and Kitchener might share the fate of Hicks and Gordon. Two circumstances, which will appear as the account proceeds, prevented the accomplishment of this plan. The second attack was not executed simultaneously by the two divisions of the Dervish army; and even had it been, the power of the musketry would have triumphed, and though the Expeditionary Force might have sustained heavier losses the main result could not have been affected. The last hopes of barbarism had passed with the shades of night. Colonel Broadwood, with nine squadrons of cavalry, the Camel Corps, and the Horse Artillery, had been ordered to check the Dervish left, and prevent it enveloping the downstream flank of the zeriba, as this was held by the Egyptian brigade, which it was not thought desirable to expose to the full weight of an attack. With this object, as the Dervishes approached, he had occupied the Kerreri ridge with the Horse battery and the Camel Corps, holding his cavalry in reserve in rear of the centre.