The "Hundred Days" is a term applied to the final major period of hostilities involving the Allies, and among them the Australian Corps, on the Western Front. It was during this period that the AIF along with the Canadians, were assigned as the shock troops of a major offensive that began with the Battle of Amiens on 8th August in what was termed by General Ludendorf, the German Commander, as "der schwarze tag" or the " Black Day" of the German Army.
The Somme front was selected as the focal point for the offensive because the southern edge along the Amiens - Roye road marked the boundary with the French Army, enabling close cooperation, and the terrain lent itself to the use of tanks, particularly the light and fast British "Whippet" tanks.
Indeed the operation became the scene of the first tank vs tank battle in history. One of the ponderous German A7 tanks was captured and eventually repatriated to Australia. Named “Mephisto’ by its crew, it resides to this day in the Queensland Museum
For the troops involved it marked a sea change in tactics, and the Australians appeared to be particularly suited to it. The offensive became one of speed, manoeuvre and decision rather than the grinding attrition of trench warfare. While the Australians captured a disproportionately high percentage of enemy troops, guns and ground, the cost was enormous. The Australian Corps was literally bled white and the average size of battalions shrank as casualties could not be replaced. Without conscription and relying on volunteers, the flow of which had slowed to a trickle, some Battalions were taking to the field with as few as 250-300 men, many of whom had been wounded one or more times in previous battles. A great many Gallipoli veterans were lost in this period as well.
The advance along the Somme front was rapid and spectacular. By the end of August the Australian Corps was converging on the great elbow in the Somme behind which stood the town of Peronne and the heights of Mont St Quentin, forming the key point of the Hindenburg Line defensive position.
In a spectacularly successful attack from the line of march involving two major river crossings, the Second and Fifth Divisions completely dislocated the German Hindenburg Line defences in that area, capturing the town and the heights while the Third Division swept around to the north to cover the flanks of the assaulting troops.
They then provided the launching point for major attacks across the Cambrai St Quentin Canal in collaboration with the US Army. Indeed many Australians served as advisers, attached to the inexperienced US forces. Numbers distinguished themselves in this capacity and were awarded a range of US decorations.
The Hundred Days for the Australians culminated in the attack on Montbrehain on the 5th October, after which the Australian Corps was withdrawn and rested pending further offensive tasking in November.
On the 11th November the guns fell silent with the declaration of the Armistice, and the Great War was effectively over, with finalisation coming with the signing of the Treaty of Versailles in June 1919.