As far as Aleppo, troops and supplies from Europe passed over one common route. From the Turkish point of view, therefore, the campaigns in these two countries were to some extent interdependent. This enabled the Turks to concentrate a reserve at Aleppo, ready to be moved down into either theatre of war as the exigencies of the situation might demand. Conversely, therefore, a British offensive in Mesopotamia might draw off troops destined for Palestine, or an offensive in Palestine might attract troops otherwise intended for operations in Mesopotamia. There is strong evidence that a Turco-German offensive was contemplated in Mesopotamia for 1918. In the spring of that year, however, a British offensive was undertaken in Palestine, which had the immediate effect of drawing to that country strong Turkish and German reinforcements from Aleppo. Nothing more was heard of the offensive in Mesopotamia, and, by the autumn of 1918, there was scarcely a fighting Turk to be found in that country. Just as our expedition against the Dardanelles, by engaging the enemy at a vital spot near home, had materially assisted the defence of Egypt, so did our offensives in Palestine materially assist the defence of Mesopotamia. Turning to another corner of the map of Turkey, where Europe and Asia meet in the mountains of the Caucasus, we see that the Turkish frontier here marches with that of Russia. In the earlier days of the war, the Russians carried out an important and successful advance in this neighbourhood, and, early in 1916, occupied the cities of Trebizond and Erzerum. Thus, at the time when the campaign in Palestine was embarked upon, the armies of the allies were closing in upon Eastern Turkey simultaneously from three directions, the Russian Caucasus army from the north-east, the British Mesopotamian army from the south-east, and the Egyptian Expeditionary Force from the south. Strategically, the situation seemed full of promise. But, in the winter of 1917-18, followed the disastrous collapse of Russia, and the setting free of many Turkish soldiers of good quality from all the Russian fronts for service elsewhere. We had hoped that our offensive in Syria might have been supported by the co-operation of the Russians. Instead, we felt the pinch of their defection in the stiffening of enemy resistance on our front by the transfer of good troops from the Caucasus to Palestine. There is yet another theatre of warfare in Asiatic Turkey, the operations in which exerted considerable influence on those in Palestine. The whole of the eastern shores of the Red Sea formed part of the Ottoman Empire. The southernmost sector, known as the Yemen, was the farthest outpost of that Empire. Here a few Turks and Arabs conducted a sporadic warfare against our garrison at Aden, more calculated to cause annoyance and to detain a British force of some strength than to exercise much influence upon the war as a whole.