The news of the advance of the Desert Column had been duly reported to the Mahdi and his Arab generals. A small party of English, it was said, with camels and some cavalry, were coming swiftly to the rescue of the accursed city. Their numbers were few, scarce 2,000 men. How should they hope to prevail against 'the expected Mahdi' and the conquering Ansar who had destroyed Hicks? They were mad; yet they should die; not one should escape. The delay in the advance offered ample opportunity. A great force of Arabs was concentrated. Slatin relates how several thousand men under important Emirs were detached from the army before Khartoum and marched northward eager for the slaughter of 'the enemies of God.' At Metemma the main strength of the Jaalin tribe was collected. With the reinforcements from Omdurman the total force of the Arabs actually at hand was not less than 10,000, and behind were many thousands more. They permitted the little column to advance until their retreat, if defeated, was impossible, and then, confident of victory, offered battle near the wells of Abu Klea. The Camel Corps remained halted during the morning of the 16th, and built a small fort, in which they placed their reserve of stores, and made some arrangement for the reception of wounded. At one o'clock they moved leisurely forward, passed through the rocky defile which led into the valley of Abu Klea and bivouacked. Early the next morning the force moved out in square formation and advanced upon the enemy. The most savage and bloody action ever fought in the Soudan by British troops followed. Notwithstanding the numbers and the valour of the Arabs, that they penetrated the square, and that they inflicted on the troops a loss of nine officers and sixty-five men killed and nine officers and eighty-five men wounded--10 percent of the entire force--they were driven from the field with great slaughter, and the Desert Column camped at the wells. On the morning of the 18th they rested, placed their wounded in the small fort they had built, and buried their dead. In the afternoon they continued their advance, marched all through the night, and, having covered twenty-three miles, halted exhausted, almost within sight of the river, at daylight on the 19th. Meanwhile the enemy had again collected in great strength, and an effective rifle fire was opened on the column. Sir Herbert Stewart received the wound of which a few weeks later he died. The command devolved upon Sir Charles Wilson. The position was desperate. Water was running short. The Nile was only four miles away; but the column were impeded by their wounded and stores, and between the river and the thirsty men lay the Dervish army, infuriated by their losses and fully aware of the sore straits to which their astonishing enemy was now reduced.