U.S. I Corps: 32nd, 33rd, 37th, and 43rd IDs and 158th RCT. Elements of the 11th Airborne Division dropped on Aparri on 23 June 45 and pushed south to link up with the 37th ID.
Don't imagine it was easy fighting then. Still with a bit of help from the Australians it probably would have been a bit easier.