The 15th Brigade embarked for the Western Front on 17 June 1916. Its first battle was the disastrous Battle of Fromelles. Despite his inexperience in trench warfare, he pointed out to Major H. C. L. Howard of Field Marshal Sir Douglas Haig's British Expeditionary Force staff that the width of no-man's land was too great for the assault to succeed. Major Howard agreed and, on returning to Haig's Chateau, attempted to persuade him that the attack was doomed to fail. But the commander-in-chief decided that the operation must go on, so Elliott did all that was possible to make it a success by himself going to the front line to personally inspect the lie of the land and encourage his men. He soon realised that the attack had been a complete failure, reported to that effect, and established that he was now organising the defence of the original trenches. In the end, 1,804 of the 5,533 Australian casualties were from the 15th Brigade. For his part, Elliott was made a Companion of the Order of St Michael and St George, mentioned in despatches, and awarded the Russian Order of St Anna (3rd class, with swords).