The Americal Division was formed in WW2 (May 1942) from the 132 Regiment
Illinois National Guard, 164 Regiment North Dakota National Guard, 182 Regiment
Massachussetts National Guard. Commanded by Maj. Gen. Alexander Patch, it
served on Guadalcanal. The North Dakota Guard Regiment played the key role in
smashing the largest Japanese offensive of the campaign, in October 1942. The
147 Regiment Ohio National Guard served independently on Guadalcanal, working
closely with Marine units.
Besides the Americal most of the rest of the Army's combat strength in the
South Pacific and New Guinea came from five National Guard Divisions, 41, 43
formed around Connecticut National Guard, 32 formed around Wisconsin and
Michigan National Guards (and commanded by Maj. General Edwin Harding, coauthor
of the Army Infantry Manual), 37 formed around Ohio National Guard and the 25
formed around Washington National Guard.
The 37th, 25th and 43rd fought on New Georgia, the 41 and 32 on New Guinea.