Well lets define what G3 moves:
1 AC w/ 2 Ftr
1 Cruiser (Assuming it wasn’t lost taking SZ112)
Correct? Does G2 purchase include any DD? Potentially 1?
Assuming G1 takes out the fleets in SZ’s 110, 112, 111?
UK fleets in SZ106, SZ109, SZ91 are irrelevant toss ups for this although each surviving one is beneficial to join the US fleet (see later).
UK chooses not to scramble from Scotland.
UK1 does its normal purchase of Inf + Ftr
UK1 takes Eire from Scotland
UK moves its StratB from London to Iceland
UK flys Ftr from Gibraltar to Scotland (you now have 6 Ftr to scramble over what UK2 purchase is)
France1 moves 1 Inf, 1 Ftr to Scotland
US1 purchases 2 AC, 1 TacB, 1 DD - 51 IPC
Land Eastern USA Ftr, TacB (Purchased on 1 AC).
Fly 1 Ftr, 1 TacB off the Pacific AC to the second AC
Fly StratB to Eastern USA
G2 is standard Sealion purchase that may or may not include a DD
UK2 purchases subs to place in SZ109. More the merrier because you know you’re losing London anyways and you plan to trap its invasion force there anyways.
US2 purchase can be 3 StratB in Eastern US, and whatever else you want (recommend pacific fleet)
US2 stages 2 AC w/ 2 Ftr/TacB, 1 Cru, 1 DD, 1 Trn w/ 1 Art/Inf in SZ102
G3 Sealion lands in either SZ110 or SZ109. Germany has a multitude of choices at this point. If it lands the fleet from 110 it won’t be taking Scotland and or Eire this round. This allows the French Inf to play blocker from the tanks you plan to strand on London. This protects the US StratB’s and allows them to land on Eire and only face German aircraft on G4. Germany lands via SZ110 also because it can place 3 DD there that it purchases in G3.
SeaLion commences, London falls.
UK3 sends its subs from SZ109 plus its StratB into SZ110. Scotland has 2 Ftrs to bring also. UK can potentially clear the fleet, but even if it doesn’t, US3 is coming right behind it to mop up.
Now lets look at what the UK is probably sending and what Germany has:
Assuming the UK ended UK1 with 27 IPC to spend, it can put 4 subs out on UK2. Its also flying 2 Ftr from Scotland 1 StratB from Iceland. Germany, landing in SZ110 probably has 1 AC w/ 2 Ftr, 1 BB, 3-4 DD and maybe a Cruiser depending if it survived. Looking at worst case scenario (G2 included a DD and the G1 Cruiser lived):
G3 ends its Sealion with:
UK sends 4 Subs, 1 StratB, 2 Ftr. Likely you get 2, maybe 3 hits on the fleet, absorbed by the AC and BB (effectively the fleet lost 16 IPC worth of value). Fleet does not repair.
US3 comes in with 2 Ftr, 2 TacB, 4 StratB. I took out two DD from my calculator to account for the 2 hits from the UK units (assuming worst case scenario).
Long as the UK attack landed 2 hits, the Germany flotilla only has a 30% chance of surviving the US hit. If the UK scores 3 hits, its down to a 10% chance to survive.
You land any of the US bombers that survive from Eastern US on Eire, allowing the French Inf in Scotland to play blocker from the stranded ground units in London. France lands its fighter on Eire or the US AC if it lost aircraft from it.
US flotilla ends up in SZ104, that can join up with any of the surviving UK units that got away from the G1 attack.
Its a multiple pronged attack here.
Moscow can also help augment this attack by buying 3 Subs on R1 and place them in SZ127. R2 can stage 4 subs in SZ125 which are in position to hit the German fleet in SZ110.
If G3 sealion ends up in SZ109 instead of 110, it is better for the allies because the 3 DD that G3 may place in SZ110 from Normandy. This makes the fleet a sitting duck and puts the US fleet out of range from German fighters that probably went to Holland and not Normandy.
This is a general outline, and I haven’t played it yet