[Cronos]

I think even Hitler after 1940 realized a cross channel invasion would be very difficult. Even if the Luftwaffe had established air superiority over Britain it would have been very tough. They probably would have focused on the u-boat blockade and attacking the British in the Mediterranean.

If they managed to blocade Britain sufficiently, they could have easily starved her to surrender. The US would NOT have joined in. Remember hitler was a fool -- HE declared war on US, not the other way around.

[mainepatsfan]

I've always wondered what FDR would have done if Hitler had told the Japanese they were on their own after Pearl Harbor?

The u-boats would have brought Britain to the negotiating table eventually. Look at the hell they caused the British even when Germany was also at war with the USA and the USSR.