The light was growing, and the mist hanging over the zariba was gradually rolled by the breeze back on to the swamp. Shouts arose from the foremost ranks of the Manyema as they saw their enemy, who responded with a bellowing roar. On came the hostile host, and Tom marked every foot of their progress, ready at the right moment to give the word to his eager troops. The Manyema would charge, he knew; he made up his mind that the force of their charge must be broken ere they came too near, so that they might have less energy for hand-to-hand fighting. The effective range of his muskets was no more than three hundred yards, but he had a few Winchesters, captured after the siege and in the rout of De Castro's force. When the enemy was within about a third of a mile of the zariba, Tom ordered twenty picked riflemen to open fire. A sharp volley rang across the plain; several men in the front ranks of the Manyema dropped, and there was an instant reply.

"Down, men!" shouted Tom, immediately after his men had fired. Not a head was visible above the parapet, and the enemy's scattered volley passed harmlessly over the camp. Many of the bullets, indeed, were nearly spent when they struck the earthwork; and Tom concluded that the best-armed among the Arabs were certainly not in the van.

He threw a hasty glance at the Arab reserve, now about half a mile away. It was advancing leisurely to the support of the main force, as though the leader expected the zariba to be carried easily at the first shock of the huge mass. Only two faces of the zariba were threatened, and Tom, seeing that there was no immediate danger of an attack from the south, ordered the musketeers on that face to issue from their gateway and post themselves behind the stakes at the corner, whence they could bring a flanking fire to bear on the dense crowd approaching. At the same time he moved the pikemen-grenadiers on this face to the eastern front, to assist in meeting the expected rush, and ordered part of his reserve to sally out by the north gate, and, lining the edge of the swamp, to threaten the flank of the attack.

Rapidly as these movements were carried out, they were barely completed when the Manyema broke into a run, and with fierce exultant yells surged forward, firing as they came. Their fire was wild and unsteady, while Tom's riflemen, taking careful aim from their position behind the earthwork, did much execution among them. The remainder of the musketeers, stooping behind their shelter, eagerly expected the order to fire, but Tom stood silent and watchful, waiting until the enemy were well within range. Even in that tense moment he felt proud of his men's self-restraint. Then, when the shouting negroes were within two hundred yards of the zariba, the long-awaited order was given. A sheet of flame burst from the two sides of the zariba on which the attack was directed. There were many gaps in the advancing ranks, but so dense was the throng that these were instantly filled up, and the Manyema came on like a swiftly-moving wall. There was no time for Tom's musketeers to reload. At fifty yards he gave the word to his grenadiers, who were stooping, match in hand, their eyes fixed on his face, their limbs strained like springs. At the command, three hundred grenades were hurled into the seething mass, and amid the deafening clatter of the explosions the grenadiers seized their pikes and stood close to stem the advancing torrent. Yelling with fury, the horde swept forward. Standing grim at his post, Tom wondered whether anything could resist the impending shock, and glanced with a momentary anxiety at his embattled ranks. But there he saw no sign of flinching, nothing but gleaming eyes, and hands clenched firmly about their weapons.

Suddenly the centre of the enemy's line came upon the row of stakes at the north-eastern corner of the zariba, so cunningly planted that in their impetuous rush the Manyema failed wholly to perceive them. The advancing wave broke like surf upon the shore; the onrushing force split into two sections, with a confused heap in the centre, stumbling helplessly over the sharp points, screaming with pain, yet pushed on by their comrades behind, these in their turn to fall upon the stakes. As they struggled there, a heavy fire broke from the musketeers who, pushed out from the southern face, had just taken up their position behind the stakes at their corner. A moment later an answering volley came from the ranks of the reserve thrown out on the north side. Bullets fell thick among the maddened heap. Five hundred yards away the Arab leader recognized that his main body was in imminent danger of rout, and hurried forward a portion of his reserve. But it was too late. His riflemen could not fire without doing more damage among their own friends than among the Bahima. Before they had covered half the distance separating them from the zariba, the vanguard was in full flight, rushing pell-mell from the withering rifle-fire, bursting into the ranks of the reserve, and sweeping them away in their mad dash for safety. Fierce yells followed them; the musketeers behind the earthwork had had time to reload, and, leaping up, poured a volley into the retreating ranks. Some of the pikemen were preparing to fling themselves over the fence in pursuit, but a curt word from Kuboko fixed them to their posts. Tom saw, a quarter of a mile away, some fifteen hundred well-armed men, the flower of the Arab force, and recognized that before he could get his own troops clear of the zariba the broken ranks of his enemy might re-form and return with the supporting force to outflank and crush the Bahima, by superior numbers, to say nothing of superior armament, which in the open would tell much more in the enemy's favour. He therefore checked the incipient pursuit, and ordered the troops he had thrown out on each flank to return within the shelter of the zariba.

It had been a breathless moment. Not a quarter of an hour had elapsed since the advancing tide had rolled towards him in the full confidence of victory, and now it had rolled back again, leaving four hundred strewn over the field.

"Well done, my men!" cried Tom, and a great shout rose from his exultant troops. Their loss had been but slight. Tom ordered the wounded to be attended to, and allowed the panting warriors to drink their fill of water.

He was under no illusions upon the situation. The first attack, an impetuous rush en masse, had been repelled; but he knew that he was not dealing with mere savages, or even with Arabs of the Soudan, but with experienced warriors who had borne the brunt of many a fight, and who had every motive for nerving themselves for a second and more formidable onslaught. It was now broad daylight; the sun lay large and red upon the horizon. In the distance Tom descried the Arab camp occupied only by a horde of slave carriers; between them and him was the baffled enemy, and he saw the Arab leaders slashing at their retreating troops, and adjuring them with vehement cries to rally and stand firm. The conflict was evidently still to come, and Tom was glad of the breathing-space to allow his men to rest, and to enable himself to make preparations for meeting an attack which he knew would strain the powers of his force to the uttermost.

The exertions of the Arab leaders had checked the rout among their men, who were gradually rallying and forming up on either side of the reserve. There was an interval, and then Tom saw emerging from the hostile force three tall figures, two of them wearing turbans and long white robes, the third a gigantic negro, taller even than Mwonda. Tom looked anxiously at the other two as they approached, no doubt to see for themselves the position which had so unexpectedly disconcerted their men. They drew nearer.

"That is Ahmed, I suppose," said Tom to himself. "Who is his companion, I wonder? Can it be the hakim?"