During the Spanish–American War, Navy Lieutenant Fullam served aboard USS New Orleans (CL-22) during the Santiago Campaign- the blockading and bombardment of Santiago and San Juan; earning the Spanish Campaign Medal. Chief among his assignments ashore was as acting aide to Secretary of the Navy Josephus Daniels, February 1913 late January 1914, followed by duties as Superintendent of the United States Naval Academy, which he commanded from 7 February 1914 until spring of 1915. Following this successful assignment at the USNA, Rear Admiral Fullam was ordered to report for sea duty at the San Francisco naval district to become Commander-in-Chief, U.S. Pacific Fleet Reserve Force; effective 5 June 1915. He hoisted his flag aboard USS South Dakota (ACR-9), and later aboard USS Milwaukee (C-21). As Commander-in-Chief he was highly critical of the little interest the West coast citizens held in preparing for involvement of the European war. He stated: ""It was time they awoke to the necessity for adequate preparedness...In the event of war the United States Navy would need at once 175,000 trained men.""