But even this difficulty was surmounted with patience, and the close of the second day saw him one step nearer the accomplishment of his aim--to train the negroes to sustain the assaults of a mounted enemy. It was the next stage that he found most difficult of all. A good shot himself, he sighed for rifles, that he might teach the men to shoot. With such obsolete weapons as spears and pikes he felt himself at a loss. But common sense and recollections of what he had read about Cromwell's army came to his aid. He taught the men forming the three-sided square to stand fast with their pikes planted obliquely in the ground, supported with the left hand, while they held in the right their short stabbing spears. Meanwhile he practised the twenty selected men in pushing out in advance, casting their spears, and then running back for refuge into the square. The whole force learnt to lie down at the word of command, to rise, to advance, to retire. In order to accustom them as much as possible to the conditions they would have to meet, he got the chief to send into the neighbourhood to hunt up or purchase horses. Such of the men as could ride he mounted, and he organised sham charges, so that the men on foot grew used to the approach of horses at the gallop. By the end of the fifth day the negroes had entered into all these exercises with spirit and enjoyment. Nothing pleased them better than the charges of the few horsemen. The spearmen would advance some twenty paces in front of the pikemen, pretend to discharge their spears when the horsemen came within range, then turn and run back between the open ranks of the pikemen, whose weapons were planted at an angle calculated to transfix the oncoming horses and men. When the spearmen had run behind the pikemen, they would wheel round and discharge another flight of spears. The horsemen carried their sham charge to within a few yards of the spears before they reined up. In their ardour, indeed, they sometimes failed to obey promptly the order to halt, and one or two of them received ugly wounds. But they took these in good part, and, when the day's work was done, were to be seen proudly displaying their injuries to their relatives. "I only hope they will be as cheerful in the real thing," thought Challis. CHAPTER XX THE MYSTERY DEEPENS When Challis and John crept down the hill that dark night, Royce remained for some time at the wall, listening anxiously for sounds which would indicate whether the Tubus had discovered them. For a time all was silent; there was not even a rustle; he hoped all was well. But presently the thud of galloping horses and the shouts of men sent a shiver down his spine. Was his friend being pursued?