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.
The Kerreri ridge, to which reference has so frequently been made, consists of two main features, which rise to the height of about 300 feet above the plain, are each above a mile long, and run nearly east and west, with a dip or trough about 1,000 yards wide between them. The eastern ends of these main ridges are perhaps 1,000 yards from the river, and in this intervening space there are several rocky under-features and knolls. The Kerreri Hills, the spaces between them, and the smaller features are covered with rough boulders and angular stones of volcanic origin, which render the movements of horses and camels difficult and painful.
The cavalry horses and camels were in the dip between the two ridges; and the dismounted men of the Camel Corps were deployed along the crest of the most southerly of the ridges, with their right at the desert end. Next in order to the Camel Corps, the centre of the ridge was occupied by the dismounted cavalry. The Horse Artillery were on the left. The remainder of the cavalry waited in the hollow behind the guns.
The tempestuous advance of Osman soon brought him into contact with the mounted force. His real intentions are still a matter of conjecture. Whether he had been ordered to attack the Egyptian brigade, or to drive back the cavalry, or to disappear behind the Kerreri Hills in conformity with Ali-Wad-Helu, is impossible to pronounce. His action was, however, clear. He could not safely assail the Egyptians with a powerful cavalry force threatening his left rear. He therefore continued his move across the front of the zeriba. Keeping out of the range of infantry fire, bringing up his right, and marching along due north, he fell upon Broadwood. This officer, who had expected to have to deal with small bodies on the Dervish flank, found himself suddenly exposed to the attack of nearly 15,000 men, many of whom were riflemen. The Sirdar, seeing the situation from the zeriba, sent him an order to withdraw within the lines of infantry. Colonel Broadwood, however, preferred to retire through the Kerreri Hills to the northward, drawing Osman after him. He replied to that effect.
The first position had soon to be abandoned. The Dervishes, advancing in a north-easterly direction, attacked the Kerreri Hills obliquely. They immediately enveloped the right flank of the mounted troops holding them. It will be seen from the map that as soon as the Dervish riflemen gained a point west and in prolongation of the trough between the two ridges, they not only turned the right flank, but also threatened the retreat of the defenders of the southerly ridge; for they were able to sweep the trough from end to end with their fire. As soon as it became certain that the southerly ridge could not be held any longer, Colonel Broadwood retired the battery to the east end of the second or northern ridge. This was scarcely accomplished when the dip was enfiladed, and the cavalry and Camel Corps who followed lost about fifty men and many horses and camels killed and wounded. The Camel Corps were the most unfortunate. They were soon encumbered with wounded, and it was now painfully evident that in rocky ground the Dervishes could go faster on their feet than the soldiers on their camels. Pressing on impetuously at a pace of nearly seven miles an hour, and unchecked by a heavy artillery fire from the zeriba and a less effective fire from the Horse battery, which was only armed with 7-pounder Krupps of an obsolete pattern, the Arabs rapidly diminished the distance between themselves and their enemies. In these circumstances Colonel Broadwood decided to send the Camel Corps back to the zeriba under cover of a gunboat, which, watchfully observing the progress of the fight, was coming down stream to assist. The distance which divided the combatants was scarcely 400 yards and decreasing every minute. The cavalry were drawn up across the eastern or river end of the trough. The guns of the Horse battery fired steadily from their new position on the northern ridge. But the Camel Corps were still struggling in the broken ground, and it was clear that their position was one of great peril. The Dervishes already carpeted the rocks of the southern ridge with dull yellow swarms, and, heedless of the shells which still assailed them in reverse from the zeriba, continued to push their attack home. On the very instant that they saw the Camel Corps make for the river they realised that those they had deemed their prey were trying, like a hunted animal, to run to ground within the lines of infantry. With that instinctive knowledge of war which is the heritage of savage peoples, the whole attack swung to the right, changed direction from north to east, and rushed down the trough and along the southern ridge towards the Nile, with the plain intention of cutting off the Camel Corps and driving them into the river.
The moment was critical. It appeared to the cavalry commander that the Dervishes would actually succeed, and their success must involve the total destruction of the Camel Corps. That could not, of course, be tolerated. The whole nine squadrons of cavalry assumed a preparatory formation. The British officers believed that a terrible charge impended. They would meet in direct collision the swarms of men who were hurrying down the trough. The diversion might enable the Camel Corps to escape. But the ground was bad; the enemy's force was overwhelming; the Egyptian troopers were prepared to obey—but that was all. There was no exalted enthusiasm such as at these moments carries sterner breeds to victory. Few would return. Nevertheless, the operation appeared inevitable. The Camel Corps were already close to the river. But thousands of Dervishes were running swiftly towards them at right angles to their line of retreat, and it was certain that if the camelry attempted to cross this new front of the enemy they would be annihilated. Their only hope lay in maintaining themselves by their fire near the river-bank until help could reach them, and, in order to delay and weaken the Dervish attack the cavalry would have to make a desperate charge.
But at the critical moment the gunboat arrived on the scene and began suddenly to blaze and flame from Maxim guns, quick-firing guns, and rifles. The range was short; the effect tremendous. The terrible machine, floating gracefully on the waters—a beautiful white devil—wreathed itself in smoke. The river slopes of the Kerreri Hills, crowded with the advancing thousands, sprang up into clouds of dust and splinters of rock. The charging Dervishes sank down in tangled heaps. The masses in rear paused, irresolute. It was too hot even for them. The approach of another gunboat completed their discomfiture. The Camel Corps, hurrying along the shore, slipped past the fatal point of interception, and saw safety and the zeriba before them.
Exasperated by their disappointment, the soldiers of Osman Sheikh-ed-Din turned again upon the cavalry, and, forgetting in their anger the mobile nature of their foe, pursued the elusive squadrons three long miles to the north. The cavalry, intensely relieved by the escape of the Camel Corps, played with their powerful antagonist, as the banderillo teases the bull. Colonel Broadwood thus succeeded in luring this division of the Dervish army far away from the field of battle, where they were sorely needed. The rough ground, however, delayed the Horse battery. They lagged, as the Camel Corps had done, and caused constant anxiety. At length two of their guns stuck fast in a marshy spot, and as several men and horses were shot in the attempt to extricate them Broadwood wisely ordered them to be abandoned, and they were soon engulfed in the Dervish masses. Encouraged by this capture, the horsemen of Osman's command daringly attacked the retreating cavalry. But they were effectually checked by the charge of a squadron under Major Mahon.
Both gunboats, having watched the Camel Corps safely into the zeriba, now returned with the current and renewed their attack upon the Arabs. Opening a heavy and accurate fire upon the river flank, they drove them westward and away from the Nile. Through the gap thus opened Broadwood and his squadrons trotted to rejoin the main body, picking up on the way the two guns which had been abandoned.