Placed out of commission on 23 June 1908, she was commissioned in ordinary on 2 March 1914. She was assigned to the Atlantic Reserve Fleet and served as receiving ship at Boston Navy Yard from 24 July 1914 – 13 March 1915. She was placed in full commission at Philadelphia on 9 May 1915 and served on Neutrality Patrol around Boston Harbor until November, when she sailed to the Asiatic Station to serve as flagship for the Commander-in-Chief of the Asiatic Fleet. She attended to regular military and diplomatic duties in China, Japan, and Russia until September 1919, when she became the flagship of Commander, Division 1, Asiatic Fleet. In January 1920, she was assigned to the Pacific Fleet as flagship of Commander, Destroyer Squadrons, and remained there until 15 January 1921. She was redesignated as CA-3 (heavy cruiser) on 17 July 1920 as part of a fleetwide redesignation plan. "Brooklyn" was placed out of commission for the final time at Mare Island Navy Yard on 9 March 1921 and sold for disposal on 20 December.