The third ship in the United States Navy named "Alert"...for the word meaning watchful, vigilant, and nimble...was an iron-hull, screw steamer built by John Roach and Son at their shipyard on the Delaware River in Chester, Pennsylvania.

The ship was authorized to be built on 10 February 1873 and the keel was laid down later that same year. On 18 September 1874, the ship slid into the Delaware River on her launching ways. Commissioning took place on 27 May 1875 with Commander William T. Sampson in command.

When commissioned, the screw steamer was 199 feet 9 inches in length overall, had an extreme beam of 32 feet, and displaced 1,020 tons. Her mean draft was 13 feet. Ship's compliment was 202 officers and enlisted men. The Alert class patrol gunboat was armed with one 11-inch smooth bore gun, two 9-inch smooth bore guns, one 60-pounder rifled gun, and spar torpedoes. Bunkers were provided for 197 tons of coal, which fueled the fires that boiled water in Babcock and Wilcox Company (Boiler Division of Barberton, Ohio) boilers, that supplied steam to the main propulsion reciprocating 500 horsepower engine manufactured by John Roach and Son, that could drive the ship at ten knots at speed. The ship was also barquentine-rigged with three masts, a bowsprit, and sails for auxiliary power and range enhancement.

The screw steamer spent the first year of her Navy career attached to the North Atlantic Station. During the summer, she flew the flag of Rear Admiral C. R. Perry Rodgers, Superintendent of the United States Naval Academy at Annapolis, Maryland...and hosted cadet- midshipmen on board for practical training in the operation of steam propulsion equipment--all as a part of the Academy's practice cruise for 1875.

USS Alert operated out of ports on the Atlantic coast of the United States during the fall and winter of 1875 and 1876 until departing New York City, New York, on 26 May 1876 on the first leg of a voyage to the Asiatic Station. Proceeding by way of the Mediterranean Sea and the relatively new Suez Canal, the ship stopped at Gibraltar, Malta, and Aden...before reaching Hong Kong on 11 September 1876. For almost three years, the ship cruised the waters around Japan and along the Chinese coast, showing the flag at such places as Yokohama, Nagasaki, Kobe, and Hakodate in Japan; and Hong Kong, Shanghai, Amoy, and Swatow in China. Unlike modern goodwill visits, her port calls frequently could be measured in terms of weeks and months rather than days. When at sea, the ship's personnel charted hydrographic features, investigated maritime disasters, and performed humanitarian services for the victims of those disasters.

On 4 January 1879, USS Alert departed Yokohama on her way back to the United States. She arrived at the Mare Island Navy Yard at Vallejo, California, on 24 February 1879, and began a six-month repair period. On 30 August 1879, the warship set sail from San Francisco, California, on her way back to the Asiatic Station. The steamer arrived in Yokohama on 6 October 1879 and commenced 32 months of service in the Far East. In addition to the normal port visits and wreck investigations, she did survey work in the Bonin Islands during the spring and summer of 1881. On 11 January 1882, USS Alert stood out of Hong Kong and embarked upon a voyage that took her to a number of places in the Orient that she had not previously visited. Her itinerary during that cruise included Saigon, Bangkok, and Singapore in southeast Asia; Batavia (now Djakarta) and Sarawak in the Netherlands East Indies (now Indonesia); and Labuan, Iloilo and Manila in the Philippines. The ship returned to Japan via Hong Kong, and, on 15 April 1882, while steaming from Kobe to Yokohama, suffered damage as a result of being rammed by the Japanese Emperor's yacht. On 15 June 1882, the patrol gunboat left Yokohama, again, for the United States. She arrived in San Francisco, California, on 18 July 1882, and, on the 31st, the vessel was placed out of commission at the Mare Island Navy Yard.

The warship remained inactive at the Mare Island Navy Yard until recommissioned on 8 October 1883 for another tour of duty on the Asiatic Station. On 23 November 1883, she put to sea on the long voyage to the Orient. The patrol gunboat arrived in Nagasaki, Japan, on 18 February 1884, and spent the next twenty months operating almost exclusively in the East China Sea and the Yellow Sea, calling frequently at Nagasaki and at Chemulpo (now Inchon), Korea. USS Alert widened her horizons in the fall of 1885 with more frequent visits to Chinese ports; and during the early months of 1886, extended her range still farther to include southeast Asian ports, notably Bangkok and Singapore. In March of 1886, the warship stopped at Hong Kong and Canton. On 19 April 1886, the patrol gunboat returned to Yokohama, Japan. That port, and Hakodate, served as the foci of her operations until the first week in August of 1886. USS Alert put to sea from the latter on 5 August 1886, and commenced a transit back to the United States. She entered San Francisco Bay on 10 September 1886 and went out of commission at San Francisco thirteen days later.

Recommissioned at the Mare Island Navy Yard on 15 January 1887, for service on the Pacific Station, the warship departed San Francisco on 23 February 1887 and headed down the coast of Mexico toward Central and South America. The Patrol Gunboat arrived off the coast of Panama --then still a province of Columbia--on 7 May of 1887.

For the next fifteen months, USS Alert plied the waters along the west coast of Central and South America between Panama and Peru keeping a watchful eye on the interests of the United States in a region of perennial turmoil.

On 11 August 1888, USS Alert set sail from Callao, Peru, bound for Hawaii--then still an independent kingdom but heavily influenced by American residents. The warship arrived in Honolulu on 15 September and remained in the Hawaiian Islands until the spring of 1889.

The ship's departure from Hawaii came in response to a maritime disaster at Samoa. Diplomatic relations strained by efforts to achieve political dominence in Samoa had brought together in Apia, Samoa, seven warships belonging to three nations. The naval strength gathered there consisted of the American ships USS Nipsic, USS Trenton, and USS Vandalia; German ships SMS Adler, SMS Eber, and SMS Olga; and the lone British man-of-war HMS Calliope. On 15 March 1889, a typhoon struck Apia trapping the three American and three German warships in the harbor. Only HMS Calliope succeeded in escaping to sea early on the

16th. By the morning of the 16th, the storm increased in ferocity and battered the six remaining vessels unmercifully. All three German ships sank, as did USS Trenton and USS Vandalia. USS Nipsic, though severely damaged, managed to beach and survive the storm.

USS Alert left Honolulu on 18 April 1889 and set a course for Samoa to provide assistance and to escort USS Nipsic to a repair facility. The patrol gunboat reached Apia on 3 May and remained there six days. On 9 May, she stood out of Apia with USS Nipsic bound for Auckland, New Zealand, but heavy seas forced the two warships back to Apia. From there, they moved to Pago Pago, whence they departed on 31 May 1889. USS Alert left USS Nipsic at Fanning Island on 14 June and continued on, alone, to Honolulu. She returned a month later, and the two warships put to sea for the last leg of the voyage to Honolulu ...where they arrived on 2 August 1889.

The patrol gunboat remained in the Hawaiian Islands until she set sail for the United States on 21 November 1889. The warship arrived in San Francisco on 9 December 1889 and was decommissioned at the Mare Island Navy Yard on 6 February 1890.

USS Alert remained at the Mare Island Navy Yard, inactive, until recommissioned on 9 October 1890...with Commander R. D. Hitchcock in command. The warship served, initially, on the Pacific Station, but departed the Mare Island Navy Yard on 18 June 1891 for a summer of duty in the Bering Sea discouraging seal poachers ... before continuing on to permanent duty on the Asiatic Station. The patrol gunboat left Unalaska on 22 August 1891 and arrived in Yokohama on 10 September of that year. The ship spent the next two years cruising the waters along the Japanese, Korean, and Chinese coasts and visiting most of the major ports in the area. As in the past, her primary missions consisted of keeping an eye on American interests and showing the flag.

In the summer of 1893, orders arrived sending the ship back to the United States. She departed Yokohama on 15 August; arrived in San Francisco on 21 September 1893; and, two days later, was placed out of commission at the Mare Island Navy Yard.

On 2 April 1894, USS Alert was recommissioned with Commander W. A. Morgan in command. Assigned to the Pacific Station once again, she returned to the Bering Sea late in May for a summer of duty suppressing seal poachers. The warship finished that assignment in mid-September and arrived back in San Francisco on the 27th. The following day, she moved to the Mare Island Navy Yard and remained there through the end of the year. On 24 January 1895, USS Alert departed the Mare Island Navy Yard to take up duty off the Pacific coasts of Central and South America. Proceeding via San Diego and Acapulco, she reached San Jose, Guatemala, on 15 February 1895. The vessel cruised along the Latin American littoral between Guatemala and Peru for over sixteen months keeping watch over American interests in the region. On 2 June 1896, she departed La Libertad, Salvador (now El Salvador), to return home. After stops at several Mexican ports, and at San Diego, she reached San Francisco on 17 July 1896.

The patrol gunboat remained in the San Francisco Bay area almost two months, spending about half that time at the Mare Island Navy Yard. Between 10 September and 10 October 1896, she made a round-trip cruise to Port Angeles, Washington State. On 18 November 1896, she stood out of San Francisco Bay on her way to conduct drills and gunnery exercises in the Hawaiian Islands. The warship arrived in Honolulu on 9 December 1896 and remained in the Hawaiian Islands through most of the first three months of 1897. On 22 March of that year, the warship left Honolulu, set a course for California, and reentered San Francisco Bay on 4 April 1897. After almost two months at San Francisco--five weeks of which were spent at the Mare Island Navy Yard--she embarked upon a voyage to Sitka, Alaska, and back.

The ship returned to San Francisco on 13 July 1897 and commenced a two-month sojourn, there. On 18 September, she headed back down the west coast of the United States to Central American waters and operated off the coast of Guatemala from 4 October to 6 November before heading back to San Francisco. USS Alert arrived there on 29 November 1897...and did not put to sea, again, until sailing for

Nicaraguan waters on 8 January 1898. She patrolled the Pacific coast of Nicaragua for almost four months before heading north once more on 29 April. USS Alert reached San Francisco on 21 May, moved to the Mare Island Navy Yard on the 23rd, and was decommissioned, there, on 4 June 1898.

Following nearly three years of inactivity, the veteran patrol gunboat was recommissioned on 11 May 1901 with Commander Gottfried Blocklinger in command. The warship was assigned to the Pacific Station as a training vessel for apprentice sailors. In that capacity, she made short cruises along the California coast until decommissioned, again, on 10 December 1903. She was berthed in the

Mare Island Navy Yard until transferred on loan to the California Naval Militia sometime early in 1907.

Although returned to the Navy on 27 February 1910, USS Alert was not reactivated until almost two years later. On 25 January 1912, she was placed in commission, in reserve, with Lieutenant Charles E. Smith in command, in connection with her fitting out for service as a submarine tender. The ship was placed in full commission as a submarine tender on 1 July 1912 with Lieutenant Charles E. Smith still in command.

When commissioned as a submarine tender, the sailing rig was gone, accommodations existed for 5 officers and 109 enlisted men, and her normal displacement was 1,110 tons. Armament now consisted of six 4-inch/40 caliber and four 6-pounder guns.

USS Alert tended submarines for the Torpedo Flotilla of the Pacific Fleet...until late in 1917. In executing her new duties, the submarine tender made short voyages along the California coast in much the same manner as she had done while serving as an apprentice training vessel. She also served, on occasion, as the submarine tender for the Third Submarine Division of the Pacific Fleet while lying alongside the wharf at Kuahua Island, United States Naval Station, Pearl Harbor, Territory of Hawaii. Submarines tended included USS K-3 (SS-34), USS K-4 (SS-35), USS K-7 (SS-38), and USS K-8 (SS-39).

The entry of the United States into World War I as an active participant on 6 April 1917 necessitated an increase of American naval strength in the Atlantic Ocean. Thus, in December of 1917, USS Alert steamed south from San Diego, transited the Panama Canal, and proceeded to Bermuda...where she took up duty as base and repair ship.

During April of 1918, USS Alert returned to the west coast of the United States and resumed duties as a Pacific Fleet Torpedo Flotilla submarine tender at the submarine base at San Pedro, California. That assignment occupied her for the remaining four years of her naval career.

The shooting phase of World War I ended on 11 November 1918.

When the United States Navy adopted the alphanumeric system of hull designations on 17 July 1920, USS Alert was classified AS-4 (Submarine Tender-4).

On 9 March 1922, USS Alert (AS-4) was placed out of commission at the Mare Island Navy Yard.

On 29 July 1922, the submarine tender was sold to the A. Bercovich Company of Oakland, California.