During the Spanish-American War, he served in Raleigh and was commended for his outstanding conduct in the Battle of Manila Bay. In 1899, he participated in scientific explorations in the Pacific under the direction of Alexander Agassiz. Then, in 1900, he returned to Alaska for work investigating its fisheries. From 1901 to 1904 he commanded Iroquois in Hawaiian waters. Next on the Asiatic Station, he served in New Orleans, Cincinnati (C 7) and Wisconsin (BB 9) and, in 1905, commanded Elcano (PG 38) on the Yangtze River Patrol.
From 1907 to 1909, he attended the Naval War College and served as Lighthouse Inspector, 6th Naval District. In 1909 he returned to the Far East to serve in turn as Captain of the Yard, Cavite, Philippine Islands, and as commanding officer of Cleveland (C 19). Captain of the Yard, Mare Island, in 1911, he assumed command of Connecticut (BB 18), flagship, Atlantic Fleet, in 1912, and of Delaware (BB 28) in 1913. Duty as Marine Superintendent of the Panama Canal followed in 1914, and in 1915 he commanded New York (BB 34). During 1916 he served on the General Board.
In 1917 Admiral Rodman served as Commander, 9th Division, Atlantic Fleet, in his flagship, New York. Ordered to European waters late in the year, his division joined the British Grand Fleet at Scapa Flow and became the 6th Battle Squadron, British Grand Fleet, under Admiral Sir David Beatty. For the remainder of World War I, Admiral Rodman commanded his division in operations in the North Sea.
Returning to the United States after the armistice, he served with the Atlantic Fleet until July 1919 when he became Commander-in-Chief, Pacific Fleet. Detached in 1921, he served as Commandant, 5th Naval District from 1921 to 1922, interrupting that duty once for a mission to Peru as Minister Plenipotentiary and Envoy Extraordinary. During 1922–23, he was senior member of a board to formulate administrative policy for all shore stations and on reaching retirement age, 64, was transferred to the retired list.
After his retirement, he continued to serve the United States and the Navy on various missions which included, in the summer of 1923, accompanying President Harding on his ill-fated inspection of Alaska. In 1937, he represented the US Navy at coronation ceremonies in London.
Admiral Rodman died at Bethesda, Maryland, 7 June 1940, and is buried at Arlington National Cemetery.