Born at Richfields, near Frederick, Maryland, Schley graduated from the United States Naval Academy in 1860, and served through the American Civil War, beginning on board the frigate Niagara in 1860 and 1861. He was attached to the frigate Potomac of the Western Gulf squadron in 1861 and 1862, and subsequently took part, on board the sidewheel gunboat Winona and the sloops Monongahela and Richmond in all the engagements that led to the capture of Port Hudson, being promoted Lieutenant on 16 July 1862.
Schley served on Wateree in the Pacific from 1864 to 1866. He suppressed an insurrection of Chinese workers on the Chincha Islands in 1865, and later in the same year landed at La Union, San Salvador, to protect American interests during a revolution.
From 1867 to 1869, he was an instructor in the United States Naval Academy. He served on the Asiatic Station from 1869 to 1872 and was adjutant of the land forces during the attack by Rear Admiral John Rodgers's expedition on the Korean forts on Salee River on 10 June and 11 June 1871.
From 1872 to 1875, he was head of the department of modern languages in the Naval Academy. He was promoted commander in June 1874.
From 1876 to 1879, he commanded Essex, most of the time in the South Atlantic on the Brazil station. During the cruise he sailed Essex to the vicinity of the South Shetland Islands in search of a missing sealer, and rescued a shipwrecked crew on the islands of Tristan d'Acunha.
From 1879 until October 1883, he was inspector of the Second Lighthouse District.
After re-supply and relief missions repeatedly failed to reach Lieutenant Adolphus Greely's Lady Franklin Bay expedition in the Arctic, Schley was appointed in February 1884 to command the next relief expedition. On 22 June, near Cape Sabine in Grinnell Land, Schley rescued Greely and six (of his twenty-four) companions, after passing through 1400 miles of ice during the voyage.
Schley was commissioned chief of the bureau of equipment and recruiting at the United States Department of the Navy in 1885, and promoted Captain in March 1888. He commanded Baltimore (C-3) in Rear Admiral George Brown's squadron off the coast of Chile in 1891. Early in 1892 he was again transferred to the Lighthouse Bureau, and until February 1895 was inspector of the Third Lighthouse District; and from 1897 to 1898 he was a member (and chairman) of the Lighthouse Board.
Schley was commissioned Commodore on 6 February 1898, and on 24 March, although lowest on the list of Commodores, he was put in command of the Flying Squadron, with Brooklyn (CA-3) as his flagship, for service in the Spanish-American War.
On 18 May 1898, Schley's Flying Squadron was sent by Acting Rear Admiral William T. Sampson to Cienfuegos to pursue the Spanish Squadron under the command of Admiral Pascual Cervera y Topete. When Sampson received news that Cervera was in Santiago de Cuba, not Cienfuegos, he initially vacillated, at first informing Schley of the rumor, yet requesting him to stay at Cienfuegos, then later changing his orders to have Schley investigate the situation at Santiago.
Although Schley was subordinate to Sampson, he was accustomed to exercising independent command of his ship. Schley decided to stay at Cienfuegos, feeling that all signs indicated that Cervera was there in the harbor. After hearing from Cuban insurgents that Cervera was definitely not at Cienfuegos, Schley decided to obey Sampson's orders three days after receiving them and go to Santiago. When the crew of three American cruisers he encountered denied knowledge of Cervera's whereabouts, Schley decided to return to Key West, Florida, to get coal for his ship. The Navy Department sent a despatch to Schley asking him to stay at Santiago, but he replied that he was unable to obey these orders. Inexplicably, Schley decided mid-voyage to return to Santiago on 28 May, where the following day it was confirmed that the Spanish Squadron was there. Sampson arrived on 1 June and assumed command. The American ships formed a blockade across the harbor to trap the Spanish ships.
On 3 July, while Sampson was en route to meet General Shafter onshore, Cervera attempted to squeeze his squadron through the blockade. Schley had assumed control in Sampson's absence. When Maria Teresa of the Spanish Squadron tried to ram Brooklyn, Schley's flagship, he ordered the ship to steer away from Maria Teresa, causing a near collision with Texas. This gave the Spanish ships added time to escape, but the American fleet, including Brooklyn, pursued the Spanish Squadron and succeeded in destroying it completely.
When the victory message from Sampson was reported, it contained no reference to any officer other than himself, even though he was not involved in the actual fighting. Sampson was loath to praise Schley's role in the fighting, a fact which derived from professional jealousy, as was evidenced later by Sampson's own conduct at the subsequent court of inquiry. Sampson was of the opinion that had it not for the Battle of Santiago de Cuba, Schley would have been court-martialed. The public, however, regarded Schley as the hero not only of the battle, but also of the war, while Sampson was seen (accurately) as indecorous for not acknowledging Schley's role.
On 14 April 1899, Schley was commissioned Rear Admiral, ranking as major general. In November 1899, he was put in command of the South Atlantic Squadron, and, in October 1901, he retired from active service upon reaching the age limit.
At Schley's request, because of the charges made against him in E. S. Maclay's History of the Navy, a court of inquiry was opened, which spent 40 days investigating Schley's conduct before and during the Battle of Santiago. On 13 December 1901, the court praised Schley's role in the sinking of the Spanish Squadron, then went on to criticize him for vacillation and "lack of enterprise," for delay in locating Cerveras squadron, for carelessness in endangering Texas and blanketing the fire of other American vessels, and for disobeying the despatch of 25 May ordering him to remain in Santiago. The court recommended that no action be taken. Admiral Schley filed a protest against the court's findings, which, however, were approved by the Secretary of the Navy, who (expectedly) supported Sampson on grounds of rank and seniority. Nonetheless, the public press, and particularly the Hearst newspapers, saw the outcome as vindicating Schley, whose status as a war hero was enhanced by the exposure.
Schley wrote, with James Russell Soley, The Rescue of Greely (New York, 1885). He also wrote and published his autobiography, Forty-five Years under the Flag (New York, 1904). For the fullest treatment of the battle of Santiago, see George Edward Graham's Schley and Santiago: an Historical Account of the Blockade and Final Destruction of the Spanish Fleet Under Command of Admiral Pasquale Cervera, July 3, 1898 (W. B. Conkey, 1902).
Admiral Winfield Scott Schley died on October 2, 1911, nine years after Admiral Sampson, who barely survived his retirement in 1902. Admiral Schley was buried with all military honors at Arlington National Cemetery, where he also has a street named for him.
There is a memorial to Schley in the lobby of the Maryland state house.