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.