Your father's unit was in the Idaho National Guard, which was inducted into Federal service as a part of the 41st Infantry at Boise, Idaho, 16 Sep 40; tranferred to Camp Murry, Wash; (the 41st Infantry also included Guard units from Wash. Oregon and Montana); relocated to Fort Lewis, Wash., 20 Mar 41, where Companies A, B and C were redesignated as the 116th Engineer Combat Battalion.
41st Infantry redesignated 41st Infantry Division, 17 Feb 42; departed San Francisco, CA, P/E, 19 Mar 42; arrived Australia, 13 May 42; landed Dobodura, New Guinea, 25 Jan 43; returned to Australia, 29 Jul 43; arrived Finschafen, New Guinea, 20 Mar 44; assaulted Hollandia, New Guinea, 22 Apr 44; asltd. Biak Island, 27 May 44; dptd. Biak Island in stages, 29 Jan/1 Feb 45; arvd. Mindoro, Philippines, 9 Jan 45; asltd. Zamboanga, Mindanao, 10 Mar 45; fought on Palawan Island and the Sulu Archpelago; arvd. Japan, 6 Oct 45, where inactivated, 31 Dec 45.
Division was at Zamboanga. Mindanao, Philippines, at war's end, 15 Aug 45.
New Guinea, 24 Jan 43 / 31 Dec 44 Luzon, 15 Dec 44 / 4 Jul 45 Southern Philippines, 27 Feb 45 / 4 Jul 45.
Killed in Action, 743 Wounded in Action, 3,504 Died from Wounds, 217. Casualty rate approximately 35%.
My reference does not identify the 116th ECBN specifically, but where the division fought, there fought the 116th you can bet.
That is all of the information I have on this unit.
I hope it helps.
With best regards,
Louie Franklin Turner
WORLD WAR II ORDER of BATTLE, Shelby L. Stanton, author, Galahad Books, NYNY, publisher. 1991.