quota for the AIF was quickly filled. The troops left for Egypt on 1 November 1914, one of the escort ships, HMAS Sydney, sinking the German cruiser Emden along the way. Meanwhile, in September, a separate Australian expeditionary force had captured German New Guinea. After arriving in Egypt, the AIF was incorporated into an Australian and New Zealand Army Corps (ANZAC) under the British general William Birdwood. The Anzacs formed part of the Mediterranean Expeditionary Force with the task of opening the Dardanelles to allied battleships, threatening Constantinople, the capital of the Ottoman Empire which had entered the war on the side of the Central Powers.The Anzacs, along with French, British and Indian troops, landed on the Gallipoli peninsula on 25 April 1915. The Australian and New Zealand position at Anzac Cove was vulnerable to attack and the troops suffered heavy losses in establishing a narrow beachhead. After it had become clear that the expeditionary force would be unable to achieve its objectives in the face of determined Turkish resistance, the Anzacs were evacuated in December, followed by the British and French in early January. The Australians suffered about 8,000 deaths in the campaign. Australian war correspondents variously emphasised the bravery and fighting qualities of the Australians and the errors of their British commanders. By 1916, Australian servicemen were commemorating 25 April, and the date soon became an Australian national holiday known as Anzac Day, centring on themes of "nationhood, brotherhood and sacrifice". In 1916, five infantry divisions of the AIF were sent to the Western Front. In July 1916, at Fromelles, in a diversionary attack during the Battle of the Somme, the AIF suffered 5,533 casualties in 24 hours, the most costly single encounter in Australian military history. Elsewhere on the Somme, 23,000 Australians were killed or wounded in seven weeks of attacks on German positions. In Spring 1917, as the Germans retreated to the Hindenburg Line, pursuing Australian troops engaged them at the First Battle of Bullecourt and the Second Battle of Bullecourt, suffering 10,000 casualties. In the summer and autumn of 1917, Australian troops also sustained heavy losses during the British offensive around Ypres. Overall, almost 22,000 Australian troops were killed in 1917. In November 1917 the five Australian divisions were united in the Australian Corps, and in May 1918 the Australian general John Monash took over command. The Australian Corps was heavily involved in halting the