The diorama depicts a scene during the 6th Brigade's attack on Mont St Quentin on 1 September 1918. It represents a tactically difficult situation as well as the daring of the Australian soldiers. The sculptor, C. Web Gilbert, said when making the diorama, “I want to satisfy not only the art critic and the military enthusiast, but the Dinkum Digger critic.” Gilbert chose Mont St Quentin first “not only because it lends itself best to picturesque treatment, but because it typifies and crowns the great sweeping victories of the A.I.F. that preceded the smashing of the Hindenburg line – and then the Armistice”.
Work began on Mont St Quentin in 1920. It was the first diorama completed for the Memorial and previously referred to as Storming of Mont St Quentin. A model of the diorama was first displayed in Melbourne and Sydney. The original figures were made of plasticine and later cast in metal for installation at the Memorial. The background was originally painted by Louis McCubbin, and then repainted by George Browning, first in 1947, and again in 1987, with Rob Slater, when the work was refurbished for relocation.
The current background by artist Arlo Mountford spans 8 hours and includes sound and animation that follows the general progression of the weather on 1 September 1918. The artist spent months exploring the Memorial’s collection and archives, reading all he could about the Battle of Mont St Quentin. The background has been animated from artworks and photographs in the Memorial’s collection including works by Louis McCubbin, Arthur Streeton and Frederick Leist as well as photographs taken of and around the day of the battle in 1918.