The significance goes back to 1915, when on the 25th of April the Australian and New Zealand Army Corps went ashore in the pre-dawn darkness at Anzac Cove, Gallipoli.
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.
Lest We Forget.