Britain declared war on Germany on the 4th August, 1914. As well as fighting on the Western front, there was an extensive campaign in Egypt against the Turkish Ottoman Empire, who were allied with Germany. One of the main objectives was to continue British control of the Suez Canal, which was a highly important supply route for goods bound for the Western front, and also for the supply of provisions to Britain.
The photograph above pictures the Turks preparing for the Raid of the Suez Canal which took place on January- February 1915, but was unsuccessful due to strong British defences. A total number of 1,192,511 British and allied men were deployed to Egypt and Palestine at some point during the war, with a peak number of 432,857 at one time.