I mentioned earlier an article in
Wargames Illustrated. It's the April, 2000 edition, #151, pp.54-6. Gary Hughs is the author. Some excerpts and paraphrasing follow.
Plan Red:
"Planning started in August 1920, and progressed . . . [for] ten years. The planners were bothered by the strength of the RN, which might pose a serious threat to American overseas possessions and trade routes, whilst regular British and Imperial troops outnumbered the American army by 3:2.
"The American planners assumed the main British objective would be the elimination of America as a commercial threat." RN would interdict or sink American merchants, while landings could be made against US overseas possessions: West Indies, Philippines and Samoa. "On the continental mainland, the main objectives would be the industrial manufacturing cities of the north east, all within easy reach of forces based in Canada, and...Washington and New York...Canadian forces [represented little threat, but] could be rapidly boosted by huge numbers of British troops:" 148,000 could be transported to Halifax within 60 days, according to US estimates.
US planners anticipated reinforcements from Australia, India, NZ, S Africa, and - weirdly - the Irish Free State (worst case scenario, I guess). American plan: all out attack prior to British reinforcements' arrival. "[O]ne army was to make Montreal and Quebec primary targets, a second was to take Winnipeg and sever the Canadian-Pacific railway. Smaller forces were to secure bridgeheads to protect Detroit, Buffalo and the Niagara power installations, and the Sault Sainte Marie canals." A contongency left to the President, but dropped as too ambitious from the main plan was to ship 25,000 men to Nova Scotia to deny Halifax to the British.
USMC was to secure the Panama Canal. Subsequent combined operations were to secure "Jamaica, the Bahamas, Bermuda, Trinidad, St. Lucia, and British Honduras" - local opposition was expected to be light, because the islands were being freed from imperial domination.
"After the intial stage of the war was successfully concluded, the army would launch further offensives in Canada to destroy all enemy forces and take Ontario, Sudbury, and Vancouver, whilst the navy would proceed with trans-Atlantic commerce raiding, or possibly even raids into the Mediterranean."
I'll post detailed problems later - redeploying the USN from Pacific to Atlantic, for example and the relative sizes of the two navies.