While some of the people were engaged in preparing this _ex tempore_ village, Tom set others to strengthen the barricade across the nullah. As he watched them, it occurred to him that the position would gain in security if he used the stream to form a moat, and he at once started two gangs digging at the extreme ends of the breastwork, a foot or two in front of it. At the close of the next day the moat was finished--a ditch six feet broad by four deep, extending right across the nullah except where the stream flowed in the centre. A man might easily leap over it, but his leap would land him amid the branches of the trees. It would be useful in checking a rush, especially if it were unnoticed until the enemy were actually upon it; and when, on its farther side, a number of low bushes and clumps of long grass had been planted, Tom found by experiment that the water was not seen until he came within half a dozen yards of it. The defences of the slopes right and left then engaged Tom’s attention. There were not enough trees on the spot to form effective barricades, and the only means of checking the enemy if they scaled the low heights was to dig trenches. The labour would be long and toilsome, for the ground must first be cleared of the brushwood; but in no other way could the enemy be prevented from swarming down into the nullah. At the end of a week the western and eastern slopes, for about thirty yards from the end of the nullah, were each scored with a deep trench, fortified with a parapet constructed of the earth that had been removed. A second line of defence might be necessary, and for this there was no better position than the bend of the nullah, nearly half a mile to the north. The sides being here steep, almost perpendicular, it was impossible to haul trees from the forest above for a breastwork like that at the entrance; so Tom had the bed of the nullah cleared of cover for a space of about two hundred yards, and a trench with a strong parapet carried from side to side. The work was still unfinished when one day the scouts, for the first time, reported that they had sighted the enemy. About ten miles away they had seen a band of young natives marching towards Bismarckburg in charge of a German officer and a small party of askaris. It seemed clear that these negroes were recruits for the German forces, and Tom, relying on the scouts’ statement that the askaris were few in number, decided to make an attempt to prevent the natives from being turned into what Captain Goltermann had called "black Germans."