Their effect upon the war was pretty "Neutral". I especially like the battle of Mataplan where Italian sailors were seen running on the decks of their cruisers carring bottles of wine. The list goes on...Taranto (Butt Whoopin), Sidi Barini (biggest mass surrender except Bataan), the Roma (pride of Italian fleet) sinking from (1) Fritz-x hit.
I've also heard that the Germans never brought "Ladies of the Evening" along with their troops, as "Hooker" (a Union General) in the U.S. Civil war did (where the "Handle" came from).
That was because they fought with the Italians, and they ALWAYS did!
Not having Italy on the Axis side would have indeed made a difference in the performance of the German Army!

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