You can order his deceased file. You'll find practical instructions at Message #2112. Go back to the Main Page, enter "2112" in the box in the upper right corner marked "Jump to #_____" then click on "Go".
The 5th Field Artillery Battalion (formerly 5th Field Artillery Regiment) was one of four assigned to 1st Infantry Division during World War II. Constituted and organized in 1861, now a parent regiment under the Combat Arms Regimental System (CARS). Elements still assigned to 1st Infantry Division.
His deceased file will include the battery he was assigned to.