England made a grave diplomatic and strategical error in the fall of 1914 in allowing Turkey to drift into an alliance with the Central Powers by default. When Turkey entered the war a few months later the British belatedly realized the disastrous effect that the closing of the Dardanelles would have on Russia's war effort, and there followed in 1914-1915 the lamentably bungled but strategically justifiable campaign to, reopen the Straits. Once this costly attempt had failed, England had no further reason for launching offensive operations against Turkey, which was nowhere an active threat to her security. Nevertheless, from the first day of the war with Turkey Britain conducted offensive operations against her in the area now known as Iraq; from 1916 she also took the offensive in Egypt-Palestine. By the end of the war these operations which contributed nothing to the crucial struggle with Germany had so swollen that they tied down three-quarters of a million British troops. In essence they were campaigns for colonial expansion, waged in the midst of and to the detriment of a war for national survival, and as such they speak volumes about the caliber of British political leadership at the time. The campaign in Mesopotamia ('Iraq), the larger and longer of the two, was initiated by the Viceregal government in India, and was controlled from Delhi until early 1916. Its immediate cause in 1914 was the fear that the Holy War declared by the Turks would spread by way of Mesopotamia and Persia to India, leading to an uprising by India's millions of Muslims, but always in the background was the desire to expand Britain's holdings in the Persian Gulf. The cumbersome division of decision-making responsibility between Britain and India provides insights into the nature and capabilities of both governments during the early part of the war, and India's incompetent direction of the military and logistical aspects of the campaign reveals very clearly the decrepitude of the British raj. Despite stubborn opposition from the Turks and Indian improvidence, the Mesopotamian campaign was brilliantly successful during its first year; it was, in fact, the only theatre of the war in which the British met with anything but reverses. By late 1915 a small British-Indian force had advanced five hundred miles up country from the sea and was within striking distance of Baghdad. In spite of the grave hazard involved in pushing this small and unsupported army even further inland, the British cabinet, seeking a propaganda victory which would compensate for the forthcoming abandonment of the Gallipoli campaign, ordered it to capture Baghdad. The British were defeated, driven back downstream, and besieged in the small town of Kut-el-Amara. The next five months until Kut's surrender were a nightmare series of increasingly hopeless and expensive attempts at relief, during which tine the forces in the country mounted from two to seven divisions. The long agony of Kut and of the Relieving Force ended on 29 April, 1916, and the British thereupon ceased offensive operations in Mesopotamia for a long time. This thesis deals therefore with two principal topics. One is the clandestine but decisive role played by Britain's imperial ambitions in the war in the Near East up to the time that the Sykes-Picot Agreement of 1916 ratified them in an inter-allied secret convention, as exemplified in the largest campaign being fought in the East at that time. The other is a study of the strategy and tactics of the campaign itself, which attempts to provide a new and clearer synthesis of the relatively scarce literature dealing with it.