Yeah there was clearly an understanding Hitler and Mussolini were going to fight together after 1937 but WWII started long before that timetable(unintentionally cause the UK and France declaring war over Poland wasn't expected). I remember reading in one of my books that Italy was supposed to be ready by 1942. Anyhow in the context of 1940, 1940 seemed like the end of the war and in many ways Hitler invading the USSR and declaring war on the USA was him expanding a conflict he'd already won. Mussolini whose entire political existence was based on Italian resentment over being sore winners in WWI who didn't get the concessions they had been promised for their reluctant involvement, was going to be hard pressed to just wait for what seemed like a chance to gobble up French and British possessions to pass. A the consequences were not foreseen, Barbarossa might have been anticipated but the USA coming to Italy sure wasn't. Also on paper the Italians had a considerably better chance of being successful in terms of taking the British colonies than it looks like they did in hindsight. Navy wise they had the ships to defeat the RN in the Mediterranean(especially given the UK's divided attention) but opposite the Germans in Jutland who outfought the British despite having really no chance they were defeated. Perhaps like Trafalagar experience was decisive and while I'm not nearly as informed on the land front perhaps the same is true there.Italy's entry into the war on the side of Germany was by no means a foregone conclusion. My understanding is that Mussolini made a somewhat irrational decision to enter the war while Italy was unprepared to fight the Allies. Also, the conventional wisdom seems to be that Mussolini was hungry for glory and did not want to stay out of the war and have Hitler take all the spoils.
So here are a couple of questions I hope will be a good incentive for a discussion:
- Could Italy have stayed out of the war and whether it could have maintained some sort of neutrality?
- If we imagine the above scenario was true, would Hitler eventually pressure Mussolini to enter the war on his side? In case of non-compliance would Germany then try to invade Italy. On the other hand, one could imagine such a scenario would be costly for Germany.
- Did elements at home pressure Mussolini to enter the war, by which I mean mostly the Fascists and Nationalists. As far as I know, Italy and Germany were previously not on friendly terms as there were points of friction between the two countries in Austria and the Balkans.
In defense of the logic of Mussolini's decision, while the Italians certainly weakened the Axis Powers possibly swinging the outcome, when Mussolini made his decision in 1940 he had no way of knowing how it ended up backfiring. The worst case scenario did not involve a land invasion of Italy as the UK would not have been able to do this without the USA(whose entry could not have been predicted as Hitler's declaration was out of nowhere), simply drive the Italians out of Africa a far different risk calculation to make. If Mussolini was aware of Hitler's intention to do Barbarossa the possibility of Germany losing to the Soviets(who in 1940 were enemies with the UK) would not have seemed like a mortal threat and as is the Soviets IMO were on exhaust fumes by the time they got to Central Europe.
Now here's the answers to your questions. That's my general take on this.
1)Yes it could have especially short term. It would have benefited Germany as Italy entering the war opened up several fronts for the Germans to deal with. Hitler knew the Italians weren't ready(heck the Germans technically weren't ready). But when Barbarossa came along Hitler would have asked them to join same as the Spanish. If the Italians had wanted they could have gotten away with staying neutral and just sending volunteers. Thing is Mussolini wasn't Franco and didn't want to stay neutral. But the conflicts that Mussolini wanted to join were inconveniences to Hitler, the one Hitler wanted(Soviets) was an inconvenience(I'd assume given there was really nothing for Italy to gain) to Mussolini. But if Mussolini wanted neutrality he could have had it, but he didn't he'd signed a secret alliance years earlier. If Italy had remained antagonistic to the Germans like pre 1938 I think Italy and the UK could have remained neutral simply because there was nothing the Germans wanted from them except not to interfere with the annexation of Austria and they while weaker were too powerful to put the effort into attacking(even Spain was). Even France might have been able to stay neutral though not sure if Hitler had some intent to attack later on for revenge. Only countrys that we know couldn't was the USSR and by 1939 Poland.
2)While this question is fueled by Germany invading Italy in 1943 when the Italians surrendered this was because the Allies were going to use Italy as a base to invade Europe and is a different situation than just attacking a neutral Italy. Don't see it happening, nothing Germany really wanted from Italy. After 1938 and giving Hitler blessing to move into Austria there really was mostly just Italian reason for the alliance to continue. If the Western front was like in WWI there would have been pressure for Italy to swoop in and end the war, perhaps this is part of why the alliance was made as an insurance measure but in our timeline this obviously wasn't necessary and Mussolini was just trying to take whatever he could before the French gave up.
3)I don't know. Mussolini's movement was based on WWI not having been worth the costs. Given how Mussolini had a situation that seemed deceivingly low risk high reward, can't imagine their having been much resistance. Remember in 1940 World War II(or the World War I continuation, I wrote a paper on the terminology it was seen as a World War:1939-x not WWII) was seen as being just about over and the UK could do nothing to German held Europe and their colonies were being seized. Without the knowledge that Hitler would escalate the war to involve the USA and USSR or least the USA the situation is fundamentally different and Italy's priority is getting to be on the winners table. While Italy embarrassed themselves on paper they should have had a chance.