In the evening of Thursday, the 7th of April, the army at Umdabia paraded for the attack on Mahmud's zeriba. The camp lay in the scrub which grows by the banks of the Atbara, as by those of the Nile, and in order to profit by the open, level ground the four infantry brigades moved by parallel routes into the desert, and then formed facing south-east in column of brigade squares, the British brigade leading. The mounted forces, with four batteries of artillery, waited in camp until two o'clock the next morning, and did not break their march. The distance from the river bank to the open plain was perhaps a mile and a half, and the whole infantry force had cleared the scrub by six o'clock. The sun was setting, and the red glow, brightening the sandy hillocks, made the western horizon indefinite, so that it was hard to tell where the desert ended and the sky began. A few gazelle, intercepted on their way to the water by the unexpected movement of troops, trotted slowly away in the distance--white spots on the rosy-brown of the sand--and on the great plain 12,000 infantry, conscious of their strength and eager to encounter the enemy, were beautifully arranged in four solid masses. Then the march began. The actual distance from the camp to the Dervish position was scarcely seven miles, but the circle necessary to avoid the bushes and the gradual bends of the river added perhaps another five to the length of the road. The pace of the advance was slow, and the troops had not gone far when the sun sank and, with hardly an interval of twilight, darkness enveloped everything. In the stillness of the night the brigades moved steadily forward, and only the regular scrunching of the hard sand betrayed the advance of an overwhelming force upon their enemies.