This guide is hard to write, because G1 and J1 has passed and it is difficult to assume how well their attacks went.
Generally speaknig I like to get fleet for the atlantic half round 1. UK needs that support to smooth things over with italy or to start getting drops in on norway/denmark or normandy/holland. I fly the bomber to london usually
Carrier. 3 destroyers. 2 subs. or bomber(s) depending on how g1 went his buy and how much air uk plans to ship off. Take brazil. pacific fleet in Hawaii.
Round 2 onwards is mostly pacific. The 2 subs are for convoy or attacking naval.
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The reason I dedicate USA 1’s buys to the europe half is because it gives UK time to react. Ideally you want UK to have italy restricted to just Europe in time to start assisting Russia with air and inf drops on europe. This may require some upkeep (such as getting more carriers and dds for uk so they arrive in front of london when he needs it).
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The pacific generally depends on you. There are two schools of thought. 1) The attack japan’s naval school 2) the indestructible fleet.
The attack Japan naval school prefers to counter attack and exchange dutch islands / phil. Usually usa clears out blockers and anzac goes in to take islands, while usa typically maintains 2-4 transports. Ideally you would want to be at carolines, but australia is fine.
The indestructible fleet school of thought will either situate itself on japan itself or hover over Java / other dutch islands to guard it.
Proponents of the sit at Japan school of thought, say that it forces Japan to make minors in SEA and build naval there to bring it up… meanwhile it forces japan to spam a bunch of infantry on its capital… also you can sometimes get an opportunity to attack and conquer japan (usually at under 30% odds, but when you are at risk of losing on the europe half… 30% for Japan to never have to worry about it again… seems pretty good). They also like to point out that USA can fly fighters to Japan waters and then to mid china and then into russia to defend russia.
The attack Japan’s naval proponents argue that exchanging islands and forcing japan to block your naval so you can exchange (sub for destroyer or 1/3 roll at fighter) is economically beneficial. Plus dropping 2 inf on phil means you lose 7 ipc for a boat, but you get 7 ipc in income and that is 2 inf japan has to figure out how to deal with. Also they usually try make enough naval to sit on carolines at the very least.
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There is a more europe centric school of thought. There are two schools.
The round japan sets up to take india and has 90% plus odds with 12 air or whatever left… uk will pull india back and try to reclaim india later with mech from persia/iraq.
The second is the hold school sometimes Russian mech/armor/air flies into India. Along with Anzac fighters (from Java). Also sometimes med/africa air flies into india as well.
For this to happen USA needs a more balanced buy to ease pressure Germany puts on Russia while simultaneously trying to disrupt what Japan does.