Folger had ordnance duty from 1873 to 1874, then took leave to travel in Europe from 1875 to 1876. He reported for duty aboard the screw sloop-of-war USS Marion in the European Squadron in 1877, then transferred to the staff of the U.S. Naval Academy for duty from 1877 to 1879. He was aboard the screw sloop-of-war USS Swatara in the Asiatic Squadron from 1879 to 1882, then served in the Bureau of Ordnance in 1882 before performing ordnance duty at Annapolis, Maryland, from 1882 to 1885. He was promoted to commander on 1 March 1885.[3][4]
At the outbreak of the Spanish–American War in April 1898, Folger took command of the protected cruiserUSS New Orleans in the North Atlantic Squadron, leading her through the end of war in August 1898, seeing service in the Flying Squadron off Cuba and in bombardments of Santiago de Cuba on 6 and 16 June 1898. He detached from New Orleans in February 1899, and then was commander of the PhilippineSquadron of the Asiatic Squadron from April to September 1899, during which time the squadron saw action in the Philippine–American War. He next was general inspector on the new battleshipUSS Kearsarge, still fitting out prior to commissioning, and became her first commanding officer when she was commissioned on 20 February 1900. He detached from Kearsarge in May 1901 and again became a lighthouse inspector, carrying out this duty in the Third District until late 1903 or early in 1904.[3][4][6][7]
Folger became commander of the Philippine Squadron of the United States Asiatic Fleet in early 1904[8] and was soon promoted to rear admiral, on 1 June 1904.[9] Later in 1904, he took command of the fleet's Cruiser Squadron.[10][11] He served briefly as commander-in-Chief of the Asiatic Fleet from 23 March 1905 to 30 March 1905.[12][13]
^The Naval Academy was located at 141 Pelham St, Newport which is the current location of the Elks Lodge, across Bellevue Avenue from the Newport Art Museum.
^She had returned to New York on 13 December to enter the yards for maintenance and repairs to battle damage from her service on the Gulf Coast. At that time ships were decommissioned while in the shipyard. She was recommissioned in July 1865 to serve as flagship of a newly organized Asiatic Squadron until August 1868.
"Folger, William Mayhew". Naval History and Heritage Command: Officers of the Continental and U.S. Navy and Marine Corps, 1775–1900. Naval History and Heritage Command. 2014-04-17. Retrieved 2015-04-06.
"Kearsarge II (Battleship No. 5)". Naval History and Heritage Command: Dictionary of American Naval Fighting Ships. Naval History and Heritage Command. 2017-12-12. Retrieved 2018-04-06.
"Rear Admiral Folger Dies at Cornish". Portsmouth Herald and Times. Portsmouth, NH: The Herald Publishing Company. July 24, 1928. p. 8. Retrieved 2013-04-06.