 On 7 April 1916 , I Anzac Corps took up positions in a quiet sector south of Armentières , known as the " Nursery " . The Australians were spared from participating in the disastrous first day on the Somme , nevertheless within three weeks of the beginning of the Allied offensive , four divisions of the AIF had been committed to the battle . Only the 3rd Division did not take part , having only just recently arrived in England from Australia . The 5th Division , positioned on the left flank of the salient , was the first to see action during the Battle of Fromelles on 19 July 1916 , suffering a staggering 5 @,@ 533 casualties in a single day . 
