Mexican–American War, 1845–1848

Portsmouth had an important role during the Mexican–American War, seizing the port of Yerba Buena (today's San Francisco) from Mexico.^[1] She had set sail on 25 January 1845 from Norfolk, Virginia, on a cruise around Cape Horn to join the Pacific Squadron under the command of Commodore John D. Sloat. En route, she made stops in Rio de Janeiro, Valparaiso, Callao, the Sandwich Islands, and Acapulco. Upon arriving off the Departamento de Las Californias coast, with Lieutenant Benjamin F. B. Hunter as her Sailing Master, she was initially engaged in watching the movements of British vessels there to prevent the possibility of Great Britain acquiring the region during any conflict between the U.S. and Mexico.

Marines of USS Portsmouth proceeding ashore on 9 July 1846 to hoist the American flag at Yerba Buena, today's San Francisco

After the declaration of war with Mexico, a detachment of Marines under the command of Second Lieutenant Henry Bulls Watson rowed ashore on 9 July 1846, marched to the pueblo's main plaza, and raised the American flag, thereby seizing the city. Renamed Portsmouth Square, the site is located in modern Chinatown. In the square there is a US Flag flown from a flagpole and a commemorative plaque set by the Daughters of the American Revolution.

Portsmouth remained in San Francisco Bay until November 1846, when she was sent to San Diego. During 1847, under the command of Montgomery, she was assigned to blockade Mexico's west coast, arriving with USS Congress and USS Argo at Guaymas on 17 October. After a request to surrender was rejected the ships began a bombardment of the city, lasting an hour. After the town surrendered a garrison was sent ashore and occupied the city.^[2] Her duty completed by early 1848, she got underway for the cruise back to the U.S. east coast on the morning of 3 January.

West Africa, 1848–1851

Returning to Boston in May 1848 she departed again on 29 August and sailed east to the African coast. There until 1 February 1849 she patrolled with Royal Navy ships to suppress the slave trade. Between September 1849 and May 1851 she again cruised off the West African coast, returning to Boston on 26 June.

Pacific, Africa, 1851–1861

Six months later Portsmouth left Boston for duty in the Pacific. On 5 April 1855 she returned to the east coast for overhaul at Norfolk, and on 3 May 1856 got underway for the Pacific again. Under Commander Andrew H. Foote she reached Batavia 94 days later, whence she sailed to China. There she participated in the engagement with the Barrier Forts of Canton on 16–22 November 1856. Ordered home in January 1858, she returned to Portsmouth, New Hampshire, and remained there until sailing for Africa again for a three-year tour, 1859–1861.

Civil War, 1861–1865

USS Portsmouth in full sail

Following the onset of the Civil War, Portsmouth home-ported and refitted between September and December 1861, then sailed for the Gulf of Mexico and duty with the Gulf Blockading Squadron. By the end of February 1862 she had captured two blockade runners off Texas. In April she participated in operations against Forts Jackson and St. Philip, then from May 1862 to August 1865 operated as station ship at New Orleans.

South America, Pacific, 1865–1878

Continuing her varied career after peace was restored, Portsmouth served as quarantine vessel at New York, 1866–67; cruised off Brazil and Africa, 1869–71; carried relief personnel to Brazil in early 1872; and participated in survey assignments in the eastern Pacific, 1873–74. This included a stop at the Palmyra Atoll for several days, arriving there on 11 December 1873. Ship's surgeon William H. Jones performed a survey of the animal and plant life, as well as creating a detailed map of the atoll's islets and lagoons.^[3] In 1875 she conducted a cruise off the west coast of Latin America and on 14 July 1878 was decommissioned as a cruiser and assigned as a training ship for boys. On 25 July 1876 at Mare Island Naval Shipyard, Boatswain's Mate Alexander Parker attempted to rescue a shipmate from drowning, for which he was later awarded a Medal of Honor.^[4]

Training ship, 1878–1915

In 1878 Portsmouth returned to the east coast, arriving at Washington, D.C., on 16 February. In March she sailed to France, returning in December to resume training ship duties on 17 January 1895, first with naval apprentices, then with the New Jersey Naval Militia, until March 1911. Three of her crewman earned the Medal of Honor during this period for jumping overboard to rescue fellow sailors: Boatswain's Mate Francis Moore on 23 January 1882,^[5] and Seaman Henry C. Courtney and Boatswain's Mate Thomas Cramen on 7 February 1882. Portsmouth was then loaned to the Public Health Service, Quarantine Station, Charleston, South Carolina to serve as a boarding launch. She was struck from the Navy List on 17 April 1915 and subsequently sold.

Portsmouth was taken to Governors Island, Boston Harbor, and burned on the night of 6–7 September 1915, the culmination of a South Boston carnival. The event was well attended by politicians and others, and a fireboat siren shrieked a salute as flames poured out of her empty gun ports.