He disappeared through the reeds in a southerly direction. It was nearly half an hour before he returned, with the news that the enemy had bivouacked on dry ground near the bank of a small stream--not the wady, but probably a tributary of it. They had just finished their morning meal: he had seen them stamp out the embers of their camp fire, yoke two horses to the aeroplane, drag it across the shallow channel, and set off northwards. They were riding in loose formation, having evidently no apprehension of meeting an enemy in this region, remote from the military operations on the Tigris some fifty miles to the east, and destitute of settled inhabitants. There was no doubt that their intention was to convey the aeroplane to the wady, which had an embankment wide enough to allow the passage of the machine. Burnet could only conclude that in default of any means of transport they would follow the course of the wady until they reached the river. Their progress must necessarily be slow, and there was plenty of time to ride back to Rejeb by a circuitous route and lay plans for a successful ambuscade. The chief's eyes gleamed when Burnet, rejoining him an hour or two later, told him the result of the reconnaissance. It seemed that the enemy must fall an easy prey. The position was admirably suited to an ambush. The ruins extended some hundreds of yards on each bank of the wady. They were fringed on the south by a dense encircling belt of reeds. In this belt, at its south-western corner, Rejeb posted the greater part of his force, mounted, the reeds being tall enough to conceal them. The remainder he ordered to dismount and place themselves under cover at the northern extremity of the ruins, at intervals of a few yards, so that they could command the southern bank of the wady with their fire. His plan was to throw the enemy into disorder by rifle fire from the north, then to hurl himself upon them with the mounted men from the south and complete their rout. These dispositions had only just been made when a new element entered into the problem. Rejeb, sitting his horse beside Burnet in the belt of reeds, suddenly turned his head sharply to the left. "What is that sound, brother?" he said. Burnet listened intently, but it was the space of a minute before his ears caught a faint throbbing murmur in the direction towards which Rejeb had turned. He recognised it instantly as the purring of a petrol-driven engine, and scanned the sky, half expecting to see a British aeroplane: perhaps a pilot had come to look for Ellingford, whose return had been expected in the lines below Kut on the previous evening. But the sky was one speckless blue, and though the sound of the engine grew louder moment by moment, there was nothing to be seen. Presently Rejeb exclaimed: "I hear horses!"