First, let us never forget that the words 'Allies' and the 'Axis' really only consisted of Britain and Germany, throughout the entire war.
All of the other allies for each chief opponent came and went throughout the war --- even changing sides or effectively going and remaining offside.
So both coalitions were actually more like fluid blobs than a solid blocks.
Prominent among the many, many reasons why Hitler, Tojo and Mussolini lost was that they were not very effective allies with each other ---- and the other minor members of the Axis were even worse, albeit often for reasons beyond their own control.
In terms of direct military, territorial and economic contributions alone, all these allies certainly aided the main Axis power, Germany.
But they also cost Germany a very great deal in terms of direct military and economic aid to sustain them as allies.
Diplomatically - in terms of co-ordinating an overall war-winning grand strategy with Germany - they almost all were a disaster.
To take but one crucial example, Japan's decision to remain neutral when Germany attacked the USSR ensured that the USSR would survive to fight on in some muted form, even without aid from Britain and America.
And the number of times when Mussolini's madcap freelance military adventures dragged in Hitler against his will, and against his overall grand strategy, is legendary.
But one Axis ally was totally reliable and extremely effective - in fact crucial to WWII even starting : Stalin's USSR.
For two crucial years (June 1939 till June 1941) Hitler could plan and execute extremely risky military ventures because he felt assured that he wouldn't be fighting a war on two full fronts.
All he could expect from the USSR (aside from the USSR stabbing Poland's highly effective army in the back by its unexpected invasion of Eastern Poland in September 1939) was massive amounts of badly needed natural resources for his overall war effort.
WWII might have even ended that way, if not for Britain's unexpected unwillingness to come to term with or surrender to Hitler.
Hitler could have - should have - digested what he had got for a few years, languidly bombing British cities at random while building enough small landing craft to successfully launch a short distant sea invasion of the island nation.
But he choose, instead, to attack the USSR full-out with tanks and to continue to attack Britain, seemingly full-out, with bombers.
This one decision, deliberately opening up an Eurasian war on two major fronts, ensured that Hitler overall became the Axis's most unreliable and most costly ally, as measured over the entire length of this coalition.
I am always miffed when examinations of the Axis coalition fails to fully examine active intermittent allies like the USSR as well as friendly (nominally Neutral) quasi members like Spain .
Too many writers prefer to renew the traditionally shopworn and limited examination of the behavior of the three main partners.
Because no similar study of the Allies ever fails to account for Neutral America's semi official but crucial help to Britain between 1939 and 1941.
Surely, we should fully include the USSR's help to Germany in the same period.
We can't continue to let abject apologists for the evils of communism and marxism continue to rule the academic roost, ensuring that Stalin's role in the early Axis is downplayed in tenure-seeking PhDs.
For during that crucial two year period, any fair observer would admit that Stalin gave far more assistance to Hitler than FDR ever gave to Churchill......