I have just run some numbers for a G2 Sea Lion attempt by Germany, in a “best case” scenario for Germany.
Assumptions:
5 TRN build on G1.
NO FIGs lost by Germany in turn 1 (not likely, but still assumed it)
Med Fleet moves west and is able to participate in the landing
No Allied fleet blocking eithr Baltic or Med Fleet units.
UK built all INF and did not attack at all, and kept their Navy safely out of range.
US sent 1 FIG, 1 BOM, 2 INF, 1 ART, 1 ARM to UK.
Even with Germany having the ability to land 14 land units (7 INF, 7 ARM), 6 FIGs, 1 BOM, and a BB shot, the chance of taking London on G2 is…
16.2%
But again, that assumes that Germany lost NO AF on turn 1, that ALL FIGs land in Western or Norway on G1 so as to be in range of London, and that the Med Fleet sailed West, destroyed the UK BB without loss, AND that the US did not block the Med Fleet.
And if the US does go to Africa, blocking the Med Fleet and leaving UK to its own defenses (other than 1 US FIG and BOM to London on US1), it is STILL only a 29% win for Germany. And to get that, they pretty much have to give up Egypt on G1, and they use almost 100% of their ARM, and they DO use 100% of their AF in the attempt.
I am sorry, but for a less than 1 in 3 chance to win early, the cost of a Sea Lion attempt with a 5 TRN buy on G1 is simply too high… it is a cost of Germany LOSING the game when they fail to take London on G2.
Lastly, even if they DO take London on G2, the US can counter on US2, and the Brits can move into the Med from the Indian Ocean, finish kicking the Germans out of Africa, and also possibly reinforce the Russians in Ukraine and/or Balkans. Germany MAY get London’s income, but they cannot keep it. And if they try to do so, the Americans will simply keep hammering them, while Russia solidifies a VERY advanced position in Central Europe.
Final Note: Raiding 30ish IPC’s from UK is NOT worth the cost in AF and land units needed.