Thomas Oliver Larkin (September 16, 1802 – October 27, 1858), known later in life in Spanish as Don Tomás Larquin,[1][2][3] was an American diplomat and businessman.

He was a descendant of Richard Warren, a passenger on the Mayflower, and his grandfather, Ebenezer Larkin, took part in the Battle of Bunker Hill.

[10][13][12] Larkin felt he had three options: marry a cousin in Massachusetts, get a job in the Washington DC post office, or join his brother in California.

[12] He received a letter from his older half-brother, John Cooper, who persuaded him that Alta California was full of opportunity, and asked for his assistance with his business.

Upon learning she was carrying Thomas' child, Rachel moved to Santa Barbara where her husband's ship was expected.

Faced with the dilemma of explaining the child to her husband, she learned in October that he had died the year before while at sea enroute from Acapulco to Lima, Peru.

[15] In Monterey, Larkin found the economics of land and commerce were controlled by the Spanish missions, presidios, pueblos, and a few ranchos.

The missionaries objected to any settlements in the country but the missions; the presidios they regarded as a necessary evil.Larkin remained in Monterey, working as a clerk for his brother John B. R. Cooper.

With an investment of $500, aided by his wife's and Captain Holmes' former accounts, he opened his own store in Monterey, selling dry goods, grog, produce, and groceries.

He never applied for Mexican citizenship, which required conversion to Catholicism; instead he renewed his visa annually to maintain his legal status.

The following year, he thwarted a British attempt to acquire California while he was assisting the Mexican government in building a smallpox hospital in Monterey.

Larkin hired William Leidesdorff as Vice Consul in San Francisco, thus relieving himself of some of the burden of the office.

He volunteered to go to Mexico City on behalf of the United States to work out a peaceful settlement, but Congress had already declared war by the time his letter arrived in Washington.

Larkin had entered into a dialog with General Mariano Vallejo with the goal of arranging a peaceful annexation of California when the Bear Flag Revolt began on 14 June 1846 and the General was captured and imprisoned by a band of Americans who had heard a rumor that the Mexican authorities were thinking of arresting all Americans.

Gillespie, after traveling in secret across Mexico and catching a ship to California, arrived early in June 1846 with the verbal messages from Polk.

Commodore (Rear Admiral) Robert Field Stockton replaced Sloat a week later as commander of the Pacific Squadron.

Stockton appointed Fremont commander of the volunteer militia formed around his 60-man Corps of Topographical Engineers and the Bear Flag Republicans as the California Battalion.

José Castro returned, and Larkin moved his family to Yerba Buena (San Francisco) as the Californios throughout the province were attempting to repel the thinly spread out California Battalion garrison troops and Navy forces.

He was later imprisoned in Los Angeles and was not reunited with his family until after the signing of the Treaty of Cahuenga which ended four months of skirmishes.

In partnership with Robert Semple, he established the city at the Carquinez Straits that became Benicia, but Larkin's business interests were in San Francisco and he sold out his share after a few years.

By the time gold was discovered, Larkin had permanently settled in the San Francisco and was in the next few years able to reap a fortune from the economic boom that followed.

Thomas acquired an acute skin disease and was so ill for two months that newspapers mistakenly announced his death.

They built an opulent mansion and enjoyed the civic improvements that had taken place in San Francisco as a consequence of the California Gold Rush since they left for New York.

[15] During this time Larkin pressed the Federal government for compensation for money he claimed he had spent on Naval supplies and for work on the Monterey Customs House and the wharf there, without satisfaction.

He was buried in what was the Laurel Hill Cemetery in San Francisco, but he is now interred at Cypress Lawn Memorial Park in Colma, California.

Children: Larkin bought a large piece of property on Calle Principal between Jefferson and Madison Streets, in Monterey, California.

The distinctive broad roof that overhangs the second floor windows and the second story balcony are stylish as well as practical and became the standard for adobe buildings of the period.

This small adobe building served as headquarters for Lieutenant William Tecumseh Sherman and military secretary of state Henry W. Halleck from 1847 to 1849.