But Royce was warned by their exultant shouts Glancing for a moment behind, he saw a dozen ferocious negroes within twenty yards of him. "Crawl up!" he said to Gambaru. Then, drawing his revolver, he turned to face the enemy. CHAPTER XV THE PROBLEM When Royce turned to face the enemy, the foremost of them was only twenty yards away, urging his horse up the slope. Behind him two score of his comrades were riding up, in no sort of order. Royce was conscious of hearing shots from behind, and of seeing two or three of the negroes reel from their saddles. Then the firing ceased, and at the same time all the Tubus leapt from their horses, and, while some held the animals, the others rushed onward on foot. They had perceived that on horseback they presented larger targets to the riflemen behind the wall. These latter could no longer fire, because Royce was now directly in line between them and the enemy. [Illustration: FACING THE FOE] Steadily awaiting their onset, Royce refrained from firing until the first man was no more than a dozen yards distant. Then he fired three shots in rapid succession, bringing down a man with each. But the rest did not quail. With strident yells they pressed about him, trusting in their numbers. It was a desperate situation. Royce had only three more shots in his revolver, and he hesitated to expend his last available resources. The Tubus had few firearms, but their spears were even more formidable weapons, and against these he had no defence. He fired for the fourth time, and a fourth victim fell. Then a spear pierced his left shoulder, and he only escaped the point of another by pistolling the negro as he was in the act of thrusting. He was about to fire his last shot, feeling that in another moment the end would come, when he heard, half unconsciously, a fierce shout behind him, and became the centre of a wild scrimmage. John, who had almost reached the wall of the fort, had turned, and, seeing his master's plight, had charged down the hill, knife in hand, into the thick of the crowd. He was a big man, and the impact of his weight overthrew two of the enemy, who staggered against their comrades, and relieved the pressure on Royce. [Illustration: JOHN TO THE RESCUE] Seizing that brief moment, Royce snatched a spear from the hand of one of the stumbling negroes, and stood beside the faithful Hausa. But the odds were overwhelmingly against them. John's sudden onset had created only a momentary diversion. The whole crowd of Tubus were flinging themselves upon the two men, when there was a second and a louder shout. A dozen stalwarts, headed by Challis hurled themselves into the _mêlée_ and laid about them lustily with clubbed rifles.