So, I know that after World War 2, Japan was forced to become a pacifist country as part of some treaty to officially end the war (I think the Treaty of Versailles?) but Germany and Italy also fought on the Axis side, but they were allowed to keep their own military. And I forget what side Russia fought on in World War 2, but I think Stalin was leading, so it might’ve been against the Allied powers. But regardless, how come Japan was the only country that fought on the Axis side of the war that lost their military? Was it because of something did in World War 1? Or was it because of Pearl Harbor? Or was there another reason?
First and foremost —- Russia was a member of the Allies. This is an important fact for the next part
At the end of WW2, Germany was fighting a war on 2 fronts. On the west against the US and UK and on the east against Russia.
After their surrender, Germany was allowed no government of its own in 1945 and was divided into four occupation zones. From 1945 to 1947, the allies tried to reduce German power in three ways: destruction of German military equipment, demobilization of armed forces, and undermining of the country's industrial capacity to make war.
So Germany did lose its military. However, Germany as one state did not exist at this time and this was the beginning of the Cold War era. NATO has influence over west Germany and the Warsaw Pact (lead by Russia) had influence over east Germany.
West Germany was a relatively free country but east Germany was under heavy Russian occupation. Due to the threat posed to the west by said Russian occupation, NATO actually helped west Germany re-found its military in 1956. And after west Germany did it, east Germany did it a year later. These two armies were not reunified until 1990
Italy has a similar answer. In short, the allies needed Italy to have an army so it got one.
In long:
Italy signed an armistice with the allies in September 1943 and split in to two territories. the Italian Social Republic – effectively a puppet state of Germany – in the north and that of the Badoglio government in the south.
This is still 2 years before Germany would surrender. So southern Italy got to keep troops to defend itself and worked with the allies. In defeating Germany. It’s more complicated then I am getting in to here but basically this bought them enough good Will to keep their army come VE Day.