On April 25, 1915, Australian and New Zealand soldiers (Australian and New Zealand Army Corps - ANZACs) formed part of the allied expedition that set out to capture the Gallipoli peninsula in order to open the Dardanelles to the allied navies. The ultimate objective was to capture Constantinople (now Istanbul in Turkey), the capital of the Ottoman Empire, an ally of Germany. It was the first major military action fought by Australian and New Zealand forces during the First World War.
The Australian and New Zealand forces landed on Gallipoli on 25 April, meeting fierce resistance from the Ottoman Turkish defenders. What had been planned as a bold stroke to knock Turkey out of the war quickly became a stalemate, and the campaign dragged on for eight months. At the end of 1915 the allied forces were evacuated, after both sides had suffered heavy casualties and endured great hardships. Over 8,000 Australian soldiers had been killed. News of the landing on Gallipoli had made a profound impact on Australians at home, and 25 April soon became the day on which Australians remembered the sacrifice of those who had died in the war.
It is the day we remember all Australians who served and died in all wars, conflicts, and peacekeeping operations. The spirit of ANZAC, with its human qualities of courage, mateship, and sacrifice, continues to have meaning and relevance for our sense of national identity.
(For more information see http://www.awm.gov.au/commemoration/anzac/anzac-tradition/ )
I believe that Anzac Day has become the most universally significant holiday for Australians because the focus is squarely on our servicemen and women and their courage and sacrifice. There is no glorification of war, nor is there political debate on Australia's part in current conflicts. We pause to reflect and remember.
They shall grow not old, as we that are left grow old;
Age shall not weary them, nor the years condemn.
At the going down of the sun and in the morning
We will remember them.