@simon33 I think maybe your preferences are so different from mine on this one that we’re having trouble communicating.
Sure, literally, it is possible for the Allies to make it impossible for Japan to take Yunnan J2 after a normal J1 opening, regardless of whether you hold an Japanese infantry back in Kiangsi. In practice, I think Allied players would very rarely want to fly the entire Russian air force to Yunnan, because holding Yunnan is worth 4 to 7 IPCs of income (depending on whether you’re playing Balanced Mod) and the ability to purchase 3 artillery instead of 4 infantry (useful, but not utterly game-changing; the entire Chinese stack shifts from an attack of about 12 punch to 17 punch, and it is slightly worse at defending).
If you stack Yunnan with literally everything that can reach as the Allies, that exposes you to strategic bombing in Russian factories on G3 and in India on J2, it makes your R3 trades much weaker and might even allow the Germans to stack one space deeper into Eastern Europe, and it makes a Japanese harbor purchase in Formosa on J2 stronger because there are no longer enough units defending India and Burma. In my opinion, these disadvantages outweigh the extra Chinese income and the extra Chinese punch.
I hear you saying that you’re somewhat interested in the question of whether to attack Yunnan with 3 land units or 4 land units on J1, but that you are pretty sure it’s wiser to attack with 4 land units when declaring J1 because without your bombers, 3 land units doesn’t give you a strong enough attack. That’s fine. I mostly agree with you about that specific point, especially if you’re insisting on taking Yunnan, rather than just clearing it.
What I’m interested in is whether it makes sense to try to capture Yunnan at all on J1 during a J1 DoW. I go back and forth on that question. I like attacking with 3 land units and 2 planes and then retreating when you are down to 1 infantry or so – you might get lucky and capture the territory, and on average you will kill more infantry than you lose. Together with a small attack on Hunan, you can bleed the Chinese pretty dry on J1 and keep Kwangsi safe for a while.
It may seem clear to you that a full J1 attack on Yunnan is obviously a good idea, but it’s not clear to me. If you want to explain more about why you’re so passionate about capturing Yunnan on J1, I’m genuinely interested to hear more about your opinions, but just declaring that “it’s one of the least close calls in the game” isn’t helpful to me.