No operation of a war is more critical than a night-march. Over and over again in every country frightful disaster has overtaken the rash or daring force that has attempted it. In the gloom the shape and aspect of the ground are altered. Places well known by daylight appear strange and unrecognisable. The smallest obstacle impedes the column, which can only crawl sluggishly forward with continual checks and halts. The effect of the gloom upon the nerves of the soldiers is not less than on the features of the country. Each man tries to walk quietly, and hence all are listening for the slightest sound. Every eye seeks to pierce the darkness. Every sense in the body is raised to a pitch of expectancy. In such hours doubts and fears come unbidden to the brain, and the marching men wonder anxiously whether all will be well with the army, and whether they themselves will survive the event. And if suddenly out of the black silence there burst the jagged glare of rifles and the crash of a volley followed by the yell of an attacking foe, the steadiest troops may be thrown into confusion, and a panic, once afoot, stops only with the destruction or dispersal of the whole force. Nevertheless, so paramount is the necessity of attacking at dawn, with all the day to finish the fight, that in spite of the recorded disasters and the known dangers, the night-march is a frequent operation. For more than two hours the force advanced, moving across smooth swells of sand broken by rocks and with occasional small bushes. Several shallow khors traversed the road, and these rocky ditches, filled with a strange, sweet-scented grass, delayed the brigades until the pace was hardly two miles an hour. The smell of the grass was noticed by the alert senses of many, and will for ever refresh in their minds the strong impression of the night. The breeze which had sprung up at sundown gradually freshened and raised clouds of fine sand, which deepened the darkness with a whiter mist. At nine o'clock the army halted in a previously selected space, near the deserted village of Mutrus and about two miles from the river. Nearly half the distance to Mahmud's zeriba was accomplished, and barely four miles in the direct line divided the combatants; but since it was not desirable to arrive before the dawn, the soldiers, still formed in their squares, lay down upon the ground. Meat and biscuits were served out to the men. The transport animals went by relays to the pools of the Atbara bed to drink and to replenish the tanks. All water-bottles were refilled, pickets being thrown out to cover the business. Then, after sufficient sentries had been posted, the army slept, still in array.