For nearly two hours Rejeb's Arabs fell back steadily. More than once the enemy sought a decision by attempting to rush the defenders, now in the centre, now at one or other of the wings. At one moment it seemed that the left wing was in danger of being crushed, but Rejeb, who throughout the day showed many of the best qualities of generalship, sent a runner to the rear to bring up a portion of his mounted reserve, now less than half a mile away. In a few minutes a hundred superbly mounted warriors galloped to the threatened point, swept like a whirlwind upon the dismounted enemy, rode through them again and again, heedless of losses, and not only defeated the flanking movement, but caused a check in the whole line. Then came word that the aeroplane had been conveyed across the causeway to the centre of the stronghold. From this moment the retreat became more rapid, though still as methodical as before. Late in the afternoon the Turks, who formed the right and right centre of the attacking force, and had fought more steadily and doggedly than their Arab allies, gained a position from which, though at extreme range, they began to command the end of the causeway. Rejeb drew nearly all his men together, posted them under cover, and concentrated his fire on the assailants on his left, in the hope of holding them off until darkness rendered it possible to slip away. At sunset, before the enemy knew what was happening, the chief withdrew his little force swiftly across the causeway. The day's work had cost him barely a score of casualties, while the enemy's losses were probably five or six times as great. "That was a top-hole rearguard action," said Ellingford to Burnet as they went together to Rejeb's tower. "I'd no idea that Arabs could ever behave so steadily." "It's due to their chief," replied Burnet. "He's got stuff in him, and he's going to be very useful. By George! I'm dead tired." CHAPTER XIII IN THE BRITISH LINES It was a week later. In one of the tents of the Headquarters staff behind the British lines Burnet, once more in Arab dress, was conversing with Captain Mitchell, an officer high in the Intelligence branch. He had just come to the end of a rather long narrative--the story of his adventures from the day when he had said good-bye to Captain Mitchell more than a month before, down to the time of the attack on Rejeb's stronghold. "And how did you get out?" asked the captain. "I slipped away to the south through the marshes, swimming the deep places on a waterskin, and wading the rest. When I was clear I steered south-east till I struck the Tigris and got aboard a country boat that was bringing up fodder." "It sounds simple, though I daresay it wasn't all what the rags at home call a joy-ride." Burnet smiled: it was not necessary to tell all that had happened during that week. "I will place the situation before the Chief," the captain went on. "You will hear from him."