"Where our good friend the Turk did us the honour of joining us, eh!" grinned Philip. "What an adventure that was, Geoff! Wish we could have more of 'em!" It was Geoff's turn to tell his friend to "Shut up!" "Don't interrupt!" he said irritably, thrusting the point of his stick deep into the mud, and pointing impatiently to the map which he had been outlining. "Let a fellow get on with his description. There's the Tigris." "You've said that already," grumbled Philip. "Well, I say it again! There it is!" "Yes, the Tigris, we all know that! Put a T against it!" That made Geoff laugh, and obediently he sketched a huge T in the sand and mud before him. "Right oh!" he said. "Tigris." "Get on," growled Philip. "Here are the marshes," and bending swiftly he scraped a row of lines in the mud. "Marshes--M--there we are, and just about here, I suppose, will be the spot where our dear friend the Turk joined us." He dug a finger deep into the mud in the midst of the patch which he had designated "marshes", and then, standing up, grinned irritatingly at Geoff. "We know all about that," he went on. "T for Tigris, M for marshes! What next? K for Kurnah, I suppose." "It's there--K!" said Geoff, laughing, for who could allow himself to be irritated with Philip? "K for Kurnah, and B for Basra. There's the head of the Persian Gulf, and there's Ahwaz. Now let's move up this line we call the Tigris. Perhaps a hundred miles up there is a place called Amara, from which the enemy can easily reinforce the troops they have in front of Ahwaz; there's nothing to prevent them but marshes and desert, and seeing that they've lived all their lives in such surroundings they know all about them. So the next move is there, to seize Amara, and make doubly secure that our pipe-line cannot be cut or damaged." As a matter of fact, the sketch-map which Geoff had drawn in the mud for the edification of his chum, was not entirely complete or informative, and we hasten at this point to supplement the information he had given. Had he prolonged the line which represented the Tigris River farther to the north and west, as it bent in that direction, he would, when he had covered sufficient space to indicate perhaps another hundred miles of desert country, have come to a place called Kut-el-Amara, where at that very moment Turks were in force; and, arrived at Kut, he would no doubt have carried on the line, making it twirl and twist in many directions--for above Kut-el-Amara the Tigris winds considerably and is most difficult of navigation--to Bagdad, that city where Major Joseph Douglas had taken up his quarters, and where the onset of this huge world war had found him an alien in a nest of enemies.