A very brief paragraph in my reference source for the 478th. reads as follows:
"478th. AAA Auto-Weapons Bn (Semimobile). (activated) 20 Nov 42 at Camp DSavis. N.C.as Sep CA Bn AA-AW. (inactivated) 4 Jan 46 at Camp Stoneham, CA. (departed) SF P/E 27 Sep 43; arrived Australia 15 Oct 43; arrived New Guinea 5 Feb 44; arvd. Philippines 22 Feb 45; arvd. SF P/E 2 Jan 46.
Was located at Cebu, The Philippines 15 Aug 45 (war's end)
Campaigns: 13,15,20 13 : Leyte , 17 Oct 44 / 1 Jul 45 15 : New Guinea, 24 Jan 43 / 31 Dec 44 20 : Southern Philippines27Feb45 / 4Jul45
He may or may not have participated in all of the above battles. You will match his death date to the chart provided in order to confirm which he was in. I would guess 13 and 15, since you mention that he died at New Guinea
My reference for this was "World War II Order of Battle", Stanton, author, Galahad Books, NYNY, publisher, which was presented to me by my daughter after purchase at Barnes&Noble.
There is other information available if the relative died and was buried overseas. I would need his name for that determination (ie, branch, unit,date died, location and number of grave site with photograph of the cemetery.