Hogaboom was promoted to lieutenant colonel and ordered to San Diego in September 1942 for duty on the staff of Amphibious Corps, Pacific Fleet under Major General Holland Smith. He was appointed assistant operations officer (G-3) and was put in charge of the amphibious training of Army 7th Infantry Division at Fort Ord, California. Hogaboom coordinated the training of the division for the ongoing Aleutian Islands Campaign and later served as an observer during the amphibious landing at Attu in May 1943. For his service in this capacity, he was decorated with the Navy Commendation Medal. He was, meanwhile, promoted to the temporary rank of colonel in November 1942.