My references state that the 25th ID was attached to I Corps from 16 June 1944. Prior to that, it was attached to Sixth Army, 11 Dec 44, and XIV Corps from 2 Jan 43, each of which was involved in the Luzon operation during Jan-45.
19 Jan 45: Philippines;LUZON: Elements of Sixth Army begin advancing south, with Clark Airfield as its objective.
20 Jan 45: US I Corps maes slow progress in the moutainous country north of the beachhead.
21 Jan 45: In the US I Corps sector, the Americans mop up the Blue Ridge, near Amlang, and one or two hills overlook ing the village of Rosario. Several Filipino battalins are now deployed among the American units.
22 Jan 45: Fierce fighting between units of I Corps and the Japanese in the area of Hill 355, near Carmen. The Americans call in artillery and tank support, but are unable to capture te hill.
23 Jan 45: There is fierce fighting in the US I Corps area, east of the beachhead, which I feel was well above Clark Airfield.
I will try to send a view of the US offensive on Luzon, which started 9 Jan 45.
Let me know how this fits the profile you have developed. OK?