European theatre of World War II
Harrison was sent overseas to the European theatre of World War II. He embarked from Boston on the USS "West Point" on September 7, 1944, and landed at Utah Beach, Normandy, on September 18, 1944. He soon engaged in the Battle of the Hurtgen Forest and by February 6, 1945, he was on the West Side of the Roer River. As part of the first Artillery Battalion of the 9th Army, he crossed the Roer on February 24.