If Japan wants all of China, they probably will end up getting it but the cost in time, material, and diverted troops will be high.
Since Japan usually diverts a lot of forces here, far greater than real life, it is only fitting the Allies look to counter: Indian mountain gun units will bolster a bit some AT capability. Some AA will make it over to too. I think the 40mm bofors are air mobile...with all the Chinese HQs who cares about the mechanized support. The air bridge will be vibrant and perhaps one of the greatest priorities of the Allied High Command in 1941 and 1942.
A nifty little trick is finding hexes that are good for Festung no retreat defenses, and hexes that threaten multiple rail or road lines. Pretty much no fort building in most bases.
I doubt I defend Chungking with a ton of troops. Ultimately, I like the Kweiyang to Paoshan line and way too many AFBs give this up. Chinese 2 AT units and Heavy Artillery will probably go here...rather than deploying them to the expected Sian push. Depending upon Japan's axis of advance they might go to the mountain road junction north of Ankang. It is a question of pool replacements which I understand to be scarce. Plus they need time to dig in at their selected hex, and also upgrade to the better field pieces. And finally, 1st and 2nd Tank Division thrust from Hong King needs to be considered.
There are 5 units I think that can be bought out and sent to India, and that will be a high priority. Several of those units start to the east, and they will be used aggressively until destroyed, respawn at Chungking and then sent west to Paoshan area.
So, this is some initial thoughts on China -- expect lots of surprises here.








