"Just!" Geoff agreed with him promptly, if not warmly, for during his short residence in Mesopotamia, when he had been with Major Joe Douglas, he had met with, and lived with, more than one tribe of Arabs, with whom he had become more than usually friendly. Moreover, he had known them to be absolutely trustworthy; and though, during this coming conflict, some might already have sided with the Turks--who were their nominal rulers--and though, as the campaign went on, it might happen that they would leave that service and join the British--for such is a habit of nomadic Arab tribes--yet that did not prove them to be utterly devoid of trust or of honour. "If I know a man at all, sir," he said respectfully, "I know this chief, whom I was instrumental in capturing. He has given us his word of honour, and he has called upon Allah to witness the words which he has spoken. That will compel him to carry out his promises whether he wills it or not; and should it happen that his followers arrest him, and do their utmost to prevent his return, yet I feel sure that he will make every effort to come back to us." As a matter of fact, some three days later, when the embarkation of the British Expeditionary Force was completed, and the troops had settled down in their camps beside the river, the outposts--placed well beyond the encampment--reported a large column of horsemen approaching. The information was brought to Head-quarters, and within five minutes of its arrival that same Intelligence Officer had sent a hurried message to our hero. "Get on your horse at once, Keith," he told him, "and come along with me. This force approaching may be our friend the chief bringing in his followers or it may be an enemy force come to try conclusions with us. If I happened to be an officer in the Indian Horse I rather think I should hope for the latter, for those boys are dying for more fighting. As it is, I trust that it will be the chief, and that he'll bring with him a lot of useful fellows. Horsemen used to the country and to the tricks of the Turks will be a valuable acquisition, and we shall be able to make the most of them." Quickly mounting the fretful Sultan, Geoff was ready within a few minutes, and, together with the Intelligence Officer, made rapid progress to the outposts. Then, fixing his glasses to his eyes, he carefully scrutinized the force approaching across the desert. A tall figure in flowing robes, riding at their head, was without doubt the chief who had given them his promise, and, having reported this fact to the Intelligence Officer, the two of them rode out to meet the cavalcade approaching. Then they led them back into the camp, and within an hour the Arabs had settled down as if they had never been anything else but a portion of the British Expeditionary Force destined to advance so far up the River Tigris.