I put this together several days ago but was sidetracked by another matter and saved it to a file. This is condensed from a four-page history of the regiment.
Very briefly, the 1st Idaho Volunteer Infantry was constituted 19 June 1877 in the Idaho Territorial Militia and organized two months later. The regiment underwent a number of changes between 1877 and 1917.
Called into Federal service for World War I, the regiment was reorganized and redesignated thusly:
1st Battalion became 1st Battalion, 146th Field Artillery (an element of the 41st Division)
2d Battalion became 2d Battalion, 116th Engineers (76th Division)
3d Battalion became 146th Machine Gun Battalion (41st Division)
Demobilized and returned to state control in 1919, the regiment was reorganized and redesignated 148th Field Artillery in 1926 and assigned to the 41st Division in 1930.
Mobilized in 1940, the 1st Battalion was redesignated 148th Field Artillery Battalion. Relieved from assignment to the 41st Infantry Division but was tactically attached to the division throughout most of the war, earning six campaign credits and participating in four amphibious assault landings in New Guinea and the Philippines.
Inactivated in Japan in 1946, the regiment was reorganized and redesignated 148th Artillery, a parent unit under Combat Arms Regimental System (CARS) in 1959.
The regiment has earned sixteen campaign credits and honors in four major conflicts between 1898 and 1945.
There's plenty information to be found but you have to RESEARCH. Very, very little is to be found on the 'net (and a great deal of that is incomplete or incorrect).