Dan came running to Dick Oakwood and cried, “Say it looks to me like a sandstorm over there. Maybe we had all better get under cover!”

Across the desert, far away, Dick saw a cloud of dust rising into the hot blue sky and called Raal.

“Is that a sandstorm?” he asked.

Raal studied the horizon carefully with narrowed eyes. “No, Master. When the sandstorm comes from the desert, it is not like that. Overhead the color changes and threatens danger. It may be a herd of wild horses that raises the dust.”

“Do wild horses run about on the desert?” asked Dan.

“Never before have I seen them, but of late I have seen many strange things. I have seen birds that carry men and I have seen the sun darkened.”

Dick took his binoculars and studied the morning cloud, but it was too far for him to make out what was kicking up the dust. Dan looked without success, and Dick turned to the natives.

“You try what you can see,” he said to Raal, handing over the binoculars.

The Taharan took the “magic glasses” with awe. Never could he outgrow the superstitious terror that they aroused.

“They won’t hurt you,” laughed Dan. “Take a chance! You saw me use them.”

“Yet they are strong magic. I fear them because I do not understand.”

“It’s all right. They are harmless to you. Look!” And as Dick helped him to focus the binoculars, Raal cried out in amazement.

“Ah-woe, ah-woe! I see warriors! Or demons, mounted on horses! The magic brings them close! Ah-woe!”

Dick took the glasses and thought he could make out what the sharp-eyed savage had seen.

“Arabs!” he gasped. “A wild tribe of nomads!”

“Arabs, Master?”

Raal did not know what he was talking about. Never had raiding Arabs found this spot so far from the caravan trails. In the history of the tribe, no strangers had ever visited the land until the airplanes had brought Dick and those others from the sky. Yet with the instinct of the savage, Raal was quick to grasp the idea of a raid by enemies.

“Arabs! If they be men, we will fight them!”

“Lucky for you we are here to protect you!” said Dan.

“Quick, Raal!” cried Dick. “Assemble the warriors with all their weapons. Spears, bows and arrows, stone hatchets and knives! Order the war drums to be sounded!”

“I hear, O Master!”

Raal hurried to obey. Shaggy blond tribesmen sprang to the hollow logs, with tightly stretched hides and soon the roll of the drums brought Taharan warriors hurrying from the fields. The alarm throbbed until the air was vibrating with a feeling of menace. The call to battle carried over the cliffs and beyond to the Gorol tree dwellings, and soon the ape-men were seen, scrambling down the steep rocks, with their war chief, Kulki, among them.

Their thin figures, covered with a fine growth of dark hair, made them resemble something more than beast and less than man. Like goats they found a footing on the steep sides. Their bodies were stringy and tough-muscled; light in weight, they were far stronger than the average civilized man, and more agile even than the Taharans.

As warriors they were formidable, and Kulki, their leader, was fearless and a tricky fighter.

Raal, too, was brave in battle and the Taharans were superb warriors. With their throwing sticks they could hurl a lance with such force that it would go right through a man’s body, and as archers they could bring down a bird in flight with their flint-tipped arrows.

“There’s trouble coming, sure!” exclaimed Dan Carter. “Jiminy, I’d hate to be an Arab and get crowned with Raal’s flint hatchet.”

But the Arabs were not fighting with such Stone-Age weapons. They carried long-barreled guns, that could pick off a bowman far beyond arrow range, and their swift horses and camels could keep them safe from attack.

“Dan, you keep close to me!” exclaimed Dick. “I’ll need you to act as my lieutenant. This is going to be a real scrap!”

Dick saw at a glance that the battle would have to be carried on from the cliffs. There the Taharans and Gorols would have the advantage of cover and the Arab horses would be useless in fighting.

Yet he knew that a sharp resistance would weaken the Arab force and lessen their confidence. The first line of battle he entrusted to Raal and a force of picked Taharan archers.

“Post your men between the desert sands and the Sacred Spring,” Dick ordered. “Let each man find shelter behind a rock and see to it that he can retreat to the cliffs at top speed. Then as soon as the enemy comes within bow-shot let drive at him with arrows and retreat, still shooting. Post a second line closer to the spring. And a third beside the water.”

“I hear, O Master. I obey!”

Without losing a moment Raal ordered his archers to find an ambush shutting off the invaders from the spring. Dick knew well that the cool water would be the first thing these raiders would want after the long trip across the blistering hot sands. No matter how full their water bags had been at the start, they would be empty now.

The spring would be the first point of attack.

Dan studied the Arabs through the binoculars. “There are hundreds of them,” he cried, “on horses and camels! They are a fierce looking gang of bandits.”

“Raal will tame them when they get within bowshot,” said Dick.

Meanwhile Kulki in command of the Gorols, took up a position on the cliff edge, while all the small children and old people of the cave dwellers, hurried to find shelter in the mountains.

The older children and the women brought big stones to the edge of the cliff to roll down upon the invaders.

All these preparations had gone forward with breathless haste, for the Arab raiders were closing in fast.

Leaving Dan behind, Dick advanced to meet them, carrying a white flag; one of the first fabrics woven on his looms. He did not want to begin hostilities until he was quite certain that the Arabs were bent on war, and waved the flag as a signal.

But Dick was not long left in doubt as to their hostile purpose.

The Arabs began shooting at the flag of truce long before they were within rifle range. Bullets threw up puffs of dust in the desert and Dick retreated to the first line, where archers were crouching behind scattered boulders, and took refuge.

The thunder of hoof beats was loud in his ears, the tossing heads and flying foam of the horses showed clearly, before Dick shouted:

“Let them have it!”

Raal echoed his command. “Let them have it! Tahara, hal!”

Instantly the band of horsemen was stung by a cloud of arrows. Horses and riders were pierced by the flint-tipped arrows and a dozen saddles showed empty as the horses galloped on.

There was a shout of rage and surprise. The raiders had expected no such fierce resistance and some shrieked to Allah and Mohammed, his prophet, while others vented screams of pain.

“Slay them! The dogs of unbelievers!” shouted Abdul, their leader.

A crackling volley of rifle shots rang out, bullets whined through the air and flattened themselves upon the boulders and the troop swerved sharply to one side.

“Another!” cried Dick. “Give it to them!”

Again arrows stung them like hornets and the Bedouins, firing wildly, were thrown into confusion.

Then as the charge broke and the riflemen galloped away to reload their weapons, Dick gave the signal to retreat to the second line of defense.

The Taharans fell back, keeping close to the ground and taking shelter at every bush and boulder.

So far the battle had been in their favor. The black-bearded ruffians had been repulsed with dead and wounded, while the Taharans had escaped without loss of a man.

Of course, luck could not favor them always. The raiders had withdrawn to take counsel with Abdul and that ferocious chieftain swore by the beard of the Prophet that he would show no mercy to the “infidel dogs” who had dared to resist him. His hawk eyes stared furiously at the cliffs, then at the boulders, behind each of which lurked a bowman.

“We will not make another charge!” he ordered. “This time each horseman will ride warily, rifle ready for action. Make a detour! Ride to one side of the rocks and try to pick off the archers one by one.”

Suli, who rode beside Abdul, searched the horizon with black, angry eyes.

“Where is Slythe?” he muttered. “The winged warrior has failed us!”

Abdul heard him and vented a hearty curse upon the missing airman.

“He has led us into a trap! May he perish and the dogs devour him!”

“He did not warn us that the savages of this tribe would fight like demons!” put in a wounded Arab, knotting a strip of linen about his bleeding arm.

“If we had known that they could fight like tigers, we would have raided them by night when they slept,” growled Abdul. “Now it is too late for a surprise or a parley. We must fight it through.”

“And first of all we must have water for ourselves and our horses!” grumbled Suli.

“Yes, by the Prophet! First we shall capture the spring. But not by storm! Ride warily and pick off the dogs one at a time!”

Carefully the troop approached and this time Dick used another strategy. As an Arab rider would approach a rock, a Taharan would break and run back to another shelter. But when the Arab chased him, firing his rifle, a second tribesman still hiding behind the rock would take a shot at the Arab at close range.

So keen and clever were the Taharan archers, that few arrows missed. But the tribesmen were not so fortunate as to go unscathed through the second attack. More than one was dropped by an Arab bullet, some to rise no more.

Dick Oakwood directed the running fight, giving orders to Raal, who shouted them to his men in a voice that rang out like the bellowing of a bull. Though he might be frightened at evil magic and things that he did not understand, Raal was brave as a lion when it came to battle.

Dan Carter had stayed in the rear according to Dick’s orders until the thrill of watching the fight got his nerves on edge with excitement. Then, armed with a bow and a quiver of arrows, he ran from one shelter to another until he was among the fighting men. At the last rock where he took refuge, a Taharan archer was already hidden, driving his arrows to the mark every time an Arab rider came within range.

Dan saw it was Kurt, one of Dick’s most trusted henchmen, and with a word of encouragement, the boy took up his position on the other side of the big rock.

“Let ’em have it!” said Dan.

“Let ’em have it!” Kurt repeated and both marksmen let fly at a Bedouin, mounted on a splendid gray horse that came charging toward the rock.

The arrows whizzed through the air, but the rider was on guard and dropped from his saddle, hanging to the side of his horse and protected by its body.

Then before the archers could shoot again he was right beside the rock and slashing out with his curving sword, struck at Kurt with a blow that laid open the tribesman’s shoulder.

Dan was ready with his second arrow by that time and let drive a dart that caught the Arab in the throat and dropped him to the ground. The horse galloped on, while Kurt and Dan ran back toward the cliffs, for now other Arabs were close by and their position was too hot to keep.

“Allah il allah!” shouted the raiders, galloping to head off the fugitives.

“Slay the dogs of unbelievers!”

Their howls of fury rose shrill and high amid the rattling of rifle shots, the whinnying of horses and the war cry of the tribesmen, “Tahara, hal! Tahara!”

Dan was racing for life, when he saw that Kurt was lagging. Loss of blood from the gash on his shoulder had weakened the Taharan warrior and it seemed as if he might fall from exhaustion, so Dan forgot his own danger to help Kurt escape.

The Arab pursuers saw that the two enemies were having a hard time to get away and let out yells of triumph.

“Allah! Down with the unbelievers!”

A couple of horsemen sped toward the fugitives and their rifles sent the echoes flying back from the cliffs, though the bullets missed their mark and sent puffs of dust from the ground to either side.

“Run, Kurt! Run for your life!” gasped Dan Carter.

“Leave me! I grow weak, but I can die like a man,” answered Kurt, brave to the last.

“You’re not going to die!” said Dan. “Here, put your weight on my shoulder. I’ll help you!”

Their situation was desperate. Behind them came the two Arabs, tugging at their scimiters to release them from the scabbards and eager to cut the fugitives to bits.

Before them raced the riderless horse, zig-zagging to avoid the tribesmen who yelled and waved their arms at it. The animal was trying to reach the spring, for it was eager for water after the long trip.

In desperation Dan dragged his wounded comrade back of a small boulder and took up his position beside him. His bow was already sending a swift arrow at the foremost rider when a yell behind him caused him to look over his shoulder.

Dick Oakwood had seen the danger that his friends were in and acted promptly. He had snatched a coiled rope, carried by one of the tribesmen, and now ran toward the riderless horse, loosening the loop as he ran. Then as the animal swerved and passed, not far away, Dick whirled the lariat, sent it flying and braced himself for the shock.

It was a good throw.

The loop settled around the animal’s neck and as Dick put his weight against it the noose tightened and the horse came down, half choked and terrified.

Before the animal could scramble to its feet, Dick was in the saddle, loosening the lariat and seizing the reins. A moment later with a new rider on its back, the Arab horse was heading back to where Dan and Kurt were standing off the Bedouin attackers.