As another response to the stalemate on the Western Front, both sides looked for new allies who might provide a winning advantage. The Ottoman Empire, hoping to drive the British from Egypt, had already come into the war on Germany’s side in August 1914. Russia, Great Britain, and France declared war on the Ottoman Empire in November. Although the Allies attempted to open a Balkan front by landing forces at Gallipoli, southwest of Constantinople, in April 1915, the campaign was a disaster. The Italians also entered the war on the Allied side after France and Britain promised to further their acquisition of Austrian territory. By 1917, the war that had originated in Europe had truly become a world conflict. In the Middle East, the dashing but eccentric British adventurer T. E. Lawrence, popularly known as Lawrence of Arabia (1888–1935), incited Arab princes to revolt against their Ottoman overlords in 1917. In 1918, British forces from Egypt destroyed the rest of the Ottoman Empire in the Middle East. For these campaigns, the British mobilized forces from India, Australia, and New Zealand. The Allies also took advantage of Germany’s preoccupations in Europe and lack of naval strength to seize German colonies elsewhere in the world. Japan seized a number of Germanheld islands in the Pacific, and Australia took over German New Guinea (see Chapter 5). Most important to the Allied cause was the entry of the United States into the war. At first, the United States tried to remain neutral, but that became more difficult as the war dragged on. The immediate cause of U.S. involvement grew out of the naval conflict between Germany and Great Britain. Britain used its superior naval power to maximum effect by imposing a naval blockade on Germany. Germany retaliated with a counterblockade enforced by the use of unrestricted submarine warfare. Strong U.S. protests over the German sinking of passenger liners—especially the British ship Lusitania on May 7, 1915, in which more than one hundred Americans lost their lives—forced the German government to suspend unrestricted submarine warfare in September 1915 to avoid further antagonizing the Americans. In January 1917, however, eager to break the deadlock in the war, German naval officers convinced Emperor William II that the renewed use of unrestricted submarine warfare could starve the British into submission within five months, certainly before the Americans could act. To distract the Wilson administration in case it should decide to enter the war on the side of the Allied powers, German Foreign Minister Alfred von Zimmerman secretly encouraged the Mexican government to launch a military attack to recover territories lost to the United States in the American Southwest. Berlin’s decision to return to unrestricted submarine warfare, combined with outrage in Washington over the Zimmerman telegram (which had been decoded by the British and provided to U.S. diplomats in London), finally brought the United States into the war on April 6, 1917. Although American troops did not arrive in Europe in large numbers until 1918, U.S. entry into the war gave the Allied Powers a badly needed psychological boost. The year 1917 was not a good year for them. Allied offensives on the Western Front were disastrously defeated. The Italian armies were smashed in October, and in November 1917, the Bolshevik Revolution in Russia (discussed later in this chapter) led to Russia’s withdrawal from the war, leaving Germany free to concentrate entirely on the Western Front.