Final answer:
Italy was the first Axis nation to be knocked out of World War 2, following the Allied invasion of Sicily and subsequent armistice on September 3, 1943.
Step-by-step explanation:
The Axis Power knocked out of World War 2 (WW2) first was Italy. Operationally, Italy was seen as the weakest link of the Axis powers. The Allied invasion of Sicily in July 1943 led to Mussolini's downfall and paved the way for Italy's surrender. After Mussolini's ousting, Italy signed an armistice with the Allies on September 3, 1943, which was made public on September 8, 1943. However, Germany swiftly occupied Northern Italy, and Mussolini was installed as the head of a puppet state, the Italian Social Republic, continuing the conflict until 1945.
Italy’s earlier exit from World War II compared to its Axis counterparts—Germany and Japan—is significant because it represents the beginning of the end for the Axis alliance and a strategic turning point in the war. The collapse of Italian resistance made it possible for the Allies to focus their resources on other fronts.