> Britain had the naval and air power to hold off Germany. Russia had sprawling territory and the winter; Britain had the English Channel. Germany would have been better served to win the North Africa campaign; that might have actually left Germany with a defensible position.

I firmly believe that the only possible route to German victory would have been capture of Gibraltar soon after the French campaign. German industries sorely needed raw materials, and it's war machine sorely needed oil. The Mediterranean could have provided both, and all the Germans needed to completely secure it would have been the Rock and Suez.

Was the capture of Gibraltar in any way realistic? With Franco joining on the German side, perhaps. The Germans had siege cannons that should have been able to reduce the foundations that Gibraltar stands on into rubble. But Franco had already won his war -- he had little to gain from joining, and a lot to lose.

Without an axis Spain, taking the Rock would essentially have required first attacking Spain. And they had a large, experienced and well-trained army, which would have had good defensive positions on the Pyrenees. I don't know.