A brother "sub" joined them at that moment, and as Geoff sketched diligently and drew in the outline of the Persian Gulf, of the Afghan frontier, and of Persia, another and yet another subaltern strolled up, till, quite unknown to him, a little group of officers were looking on over his shoulder. Then he suddenly became aware of their presence, and, colouring furiously, for the young fellow was essentially modest, he crumpled the paper up and threw it into a corner. "No you don't, my boy! No you don't!" said a well-known voice from behind his shoulder. "We are all of us keen on knowing something more about the place we are bound for, and you are the only one amongst us who has ever been there. Take it as an order, Geoff. I'll guarantee that there shall be no larking, and I'm sure that every one of your brother officers wishes you to give us just a short lecture on the country called Mesopotamia." Under the circumstances it was not to be expected that a junior officer, so junior indeed as Geoff, could refuse the request--the order if you like to call it, though it was given so pleasantly--of one of his seniors. It was the senior captain, in fact, who was leaning over his shoulder, and who patted his arm encouragingly. "Fire ahead, Geoff," he told him. "It's not showing off! There's no swank about it! I'd like awfully to know all about this Mesopotamia. I'll admit the fact, before you young officers, that I'm just about as ignorant as I can be. Up to now I never imagined that there were any Turks to speak of in the neighbourhood of the Persian Gulf, so why on earth they should send an Expeditionary Force there from India is more than I can guess at. The Colonel says it's so that we shall protect the oil-supply which comes down from Persian territory to somewhere near the Gulf. Know it, Geoff?" "Yes, sir! And if you really won't think it's swank----" "Of course not. Now, here's a piece of paper, and get on with it." [Illustration: Sketch Map of Mesopotamia]