The 33rd Infantry Division was a formation of the U.S. Army National Guard between 1917 and 1968. Originally formed for service during World War I, the division fought along the Western Front during the Battle of Amiens, the Battle of Hamel, the Meuse-Argonne Offensive, at the Second Battle of the Somme, and at the Battle of Saint-Mihiel. It was re-formed during the inter-war period, and then later activated for service during World War II, seeing action against the Imperial Japanese Army in the Pacific. In the post war era, the division was reconstituted as an all-Illinois National Guard division. In the late 1960s, the division was reduced to a brigade-sized formation, and its lineage is currently perpetuated by the 33rd Infantry Brigade Combat Team.

The Battle of Amiens, also known as the Third Battle of Picardy, was the opening phase of the Allied offensive which began on 8 August 1918, later known as the Hundred Days Offensive, that ultimately led to the end of the First World War. Allied forces advanced over 11 kilometres (7 mi) on the first day, one of the greatest advances of the war, with Gen Henry Rawlinson's British Fourth Army and Gen Marie Eugène Debeney's French First Army playing the decisive role. The battle is also notable for its effects on both sides' morale and the large number of surrendering German forces. This led Erich Ludendorff to later describe the first day of the battle as "the black day of the German Army". Amiens was one of the first major battles involving armoured warfare.