What event turned the tide for the allies in World War 1?

The turning point for the Allies in World War I is widely considered to be the Second Battle of the Marne in July 1918. This battle marked the last major German offensive of the war, following which the Allies launched a successful counteroffensive. The entry of fresh American troops and resources bolstered the Allied forces, contributing to a series of victories that ultimately led to the armistice in November 1918. The defeat of German forces in this battle signified a shift in momentum towards the Allies.