In contemplation of the removal of the waggons as soon as the advance should be made, roughly-built block-houses, made of contiguous logs placed vertically and quite bullet-proof, were constructed to substitute the shelter afforded by the former. The logs were twelve feet long, and three feet of this were buried in the ground, the buried ends being spiked into transverse beams; roughly-hewn beams formed the roofs, and over these was placed brushwood covered with four feet of earth. Green timber, of which there was an undiminished supply, was used, and, when necessary, this was covered with raw hides to prevent danger from fire. Now, as the enemy had no artillery, and was not likely to understand its employment, even if provided with the guns captured at Isandhlwana, no defence could be more suitable. An ordinary work could, it was found, be often defiladed from a neighbouring height, while a well-made blockhouse, with carefully prepared roof, was, in every case, impregnable to rifle-fire. The plan for the roofs was as follows:--The young trees or branches were placed with the roots and thick ends inwards, while the smaller ends, sharpened and shaved down thin, were allowed to project over the walls of the building till they reached to within three feet of the ground. These boughs, if thin and with smaller branches between them, would not allow the means for climbing on the roof, should the Zulus attempt it, as they would not bear the weight of a crowd of men. In positions where the blockhouse could not be commanded by any neighbouring height, the roof was made flat and surrounded with a parapet of earth, so as to afford a second tier of fire.