After a first cruise in USS Tuscarora, he was commissioned an ensign in 1876. Routine duties occupied the next several years, highlighted by a world cruise on USS Ticonderoga under Commodore Robert Wilson Shufeldt in 1878.
In 1887 he was assigned to the Bureau of Ordnance. Over the next six years, he made numerous contributions to gun mechanisms and gunnery practice, notably the Fletcher breech mechanism that increased the speed of rapid-fire guns. In 1890 the navy adopted his suggestion for the use of range lights on all vessels. He also developed the first doctrines for torpedo warfare while commanding the US Navy’s first torpedo boat, USS Cushing in 1893.
In 1896, Fletcher was assigned to the battleship USS Maine but was absent when the ship was blown up in Havana Harbor in February 1898, triggering the Spanish-American War. Alternate shore and ship tours followed, including ordnance work, command of the Torpedo Station at Newport, Rhode Island, and a year on the General Board of the Navy.
In 1910, Fletcher was appointed an aide to the Secretary of the Navy. In October 1911 he was promoted to rear admiral and until 1913 commanded divisions of the Atlantic Fleet.
In February 1913, during a period of high tension between the US and Mexico marked by President Woodrow Wilson’s refusal to recognize the government of General Victoriano Huerta, Admiral Fletcher was named commander of US naval forces in the Gulf of Mexico.
On 9 April 1914, Mexican authorities at Tampico arrested a boat crew from the USS Dolphin and refused Admiral Henry T. Mayo’s demand for a 21-gun salute to the American flag accompanying an apology. Eleven days later, after consulting with congress, President Wilson ordered Admiral Fletcher to seize the customs house at Vera Cruz.
Under the command of Colonel Wendell Cushing Neville, 787 marines and seamen participated in the initial landing. Reinforcements following in the face of stubborn Mexican resistance and by noon on 22 April, Neville’s force occupied the entire city. On 30 April, Fletcher turned over command of the city to General Frederick Funston. For his part in the Vera Cruz operations he was awarded the Medal of Honor.
In September 1914, Admiral Fletcher was named commander of the Atlantic Fleet and was promoted to Full Admiral the following March. After returning to shore duty in June 1916, he again served on the Navy General Board and on the War Industries Board during World War I.
He retired in November 1919, died in New York City 28 November 1928, and is buried with his wife, Susan Hunt Stetson Fletcher (1867–1946), in the Arlington National Cemetery.
The Papers of Frank Friday Fletcher (1873-1928) are held at the University of Virginia Library, Charlottesville, Virginia.