If you’re not Chuck or are not interested in WWII, don’t read this:
The Southern Army was established on November 6, 1941 to control all IJA units assigned to the Southern Operations. The command was headquartered in Siagon, Friench Indochina under Gen. Count Terauchi Hisaichi. The plan was certainly ambitious. The seizure of all of Southeast Asia, the NEI, the Philippines, and regions of the South Pacific would be accomplished by only 11 infantry divisions, four brigade-sized forces, and 700 IJA aircraft – 400,000 troops total. This area stretched across five time zones and was larger than the Continential United States. Japan was counting on surprise, and the relatively unprepared and weak forces fielded by the colonial powers. Its own resources would be stretched to the limit with transport shipping pulling double duty to move troops. Almost half of the IJA’s 1,500 combat aircraft would be required….
In December, 1941, Japan possessed 51 divisions supplimented by 59 brigade equivalents, but many of these were non-deployable being garrison and line-of-communications security forces in China. 28 divisions were in China with most engaged in combat or occupation duty. Another 13 were in Manchuria and Korea to protect the Empire’s northern frontier with the USSR. Two of the five divisions remaining in the Home Islands were newly raised and partly trained. The exceptions were the 2d committed to the Southern Operations, the 4th as the IGHQ Reserve and the 7th tied down protecting northern Japan from the USSR.
In other words, there were not six divisions, but five theoretically available for the hypothetical invasion of Hawaii or the West Coast. Two hadn’t finished their training. One was required for defense against the USSR, (which they’d been planning to attack until August, 1941), and the 4th was required as a reserve for the 14th Army invading the Phillipines.
“The 14th Army was designated the Phillippines Attack Force consisting of the 48th Division, 16th Division, 5th Air Group (20 air battalions) and the 4th Division (committed later). The operation was scheduled to take 50 days.”
Since the Japanese knew it would require 50 days to take the Phillipines, 5516 miles from the West Coast and very difficult to reinforce, they would have to have been completely insane to attempt an invasion that would almost precisely reverse the logistical advantage in the USA’s favor. As it turned out, it took them longer than scheduled and they were forced to throw in their reserve division.
There is no way that the Japanese would have been crazy enough to send one solitary division to attempt to take and hold Hawaii. The ease and patience with which American forces went about retaking the Aleutian Islands from the Japanese demonstrates how such an invasion would have been suicidal. The only probable effect on the course of the war would have been to hasten its end.
For details on exactly what units were where in December, 1941, I recommend Osprey Battle Orders #9, which contains copious unit descriptions as well as maps graphically depicting deployments. The deployment of the Japanese Southern Army shown below make it very clear why the US high command was so much more concerned with defending Port Moresby and Australia than Honolulu and Los Angeles.
The Japanese Army in WWII: Conquest of the Pacific 1941-1942, page 11. Osprey Publishing, 2005
Note for Chuck: the map shows the Southern Army only. Most of the units you are talking about were in the General Defense Command, distributed as follows:
Eastern District Army: 52d Division, 2d, 3d, 51st and 57 Depot divisions
Central District Army: 53d, 54th Divisions, 4th, 5th and 55th Depot divisions
Western District Army: 6th, 56th Depot divisions
Northern District Army: 7th Division, Karafuto Mixed Brigade
My understanding is that most of the divisions VG includes in the game were not combat-ready divisions, hence the designation Depot Division. But the bigger problem you face is that you have to account for the USA’s ability to reinforce Hawaii once the attack begins. First you have to find your transport and give up the Philippine invasion, then note that your transport capability only allows for two full divisions. For your air, you get the Pearl Harbor force plus two fighter, two light bomber and one heavy bomber regiment.
Remember, the entire Atlantic carrier fleet can be in Hawaii from Norfolk in only 15 days. On December 7, 1941, Wasp, Long Island, Hornet, Ranger and Charger were all available, to say nothing of the land-based aircraft on the West Coast.