August Belmont (1813-1890) war ein deutsch-amerikanischer Bankier und Politiker.

August Belmont wurde als Sohn von Simon und Frederika Schönberg geb. Elsass geboren. Er entstammte einer jüdischen Familie, als er sieben Jahre alt war starb seine Mutter. Kurz darauf zog er nach Frankfurt am Main um, wo er bei seinem Onkel und seiner Großmutter lebte. Ihre Schwägerin war mit einem Sohn von Mayer Amschel Rothschild verheiratet. Über diese Verbindung erhielt der 14-jährige August Belmont eine Anstellung beim renommierten Frankfurter Bankhaus Rothschild. Er stieg bis 1832 vom einfachen Gehilfen zum Handlungsbevollmächtigten auf und tätigte Geschäfte in Neapel, Paris und Rom.

1837 wurde er nach Havanna geschickt, um die dortige Rothschild-Filiale zu leiten. Er reiste über New York City, wo kurz vor seiner Ankunft eine schwere Wirtschaftskrise ausbrach. Er beschloss, in New York zu bleiben, änderte seinen Nachnamen in "Belmont" und gründete sein eigenes Unternehmen, die August Belmont & Company. Er übernahm zu günstigen Konditionen zahlreiche in Konkurs gegangene Unternehmen und auch die dortige Rothschild-Niederlassung.

Belmont erwarb die amerikanische Staatsbürgerschaft und wurde 1844 zum Generalkonsul Österreichs in New York ernannt. Aus Protest gegen die seiner Auffassung nach grausame Politik Österreichs gegenüber Ungarn trat er 1850 von diesem Amt zurück. Am 7. November 1849 heiratete er Caroline Slidell Perry, die Tochter des Marineoffiziers Matthew Calbraith Perry. Ihr Onkel, der Abgeordnete John Slidell, brachte Belmont dazu, sich für die Demokratische Partei einzusetzen und die Nomination von James Buchanan als Präsidentschaftskandidat finanziell zu unterstützen. Als dann jedoch Franklin Pierce zum Kandidaten nominiert wurde, wechselte Belmont das Lager.

Nachdem Pierce die Präsidentschaftswahl 1852 gewonnen hatte, ernannte er Belmont zum Chargé d'affaires der USA in Den Haag, zum Dank für den großzügigen finanziellen Beitrag während des Wahlkampfs. Belmont strebte das Amt des Botschafters in Spanien an, doch Pierces Nachfolger James Buchanan verweigerte dies. Belmont nahm 1860 als Delegierter an der Democratic National Convention teil, bei der er den demokratischen Präsidentschaftskandidaten Stephen A. Douglas unterstützte.

Im gleichen Jahr wurde er in Baltimore zum Vorsitzenden des Democratic National Committee gewählt. Dieses Amt hatte er bis 1872 inne. Belmont war während des Sezessionskriegs ein glühender Verfechter der Interessen der Unionisten und übte starken Einfluss auf die Kaufleute und Finanziers aus dem Vereinigten Königreich und Frankreich aus. Belmont starb 1890 im Alter von 73 Jahren.

In seinem Todesjahr erschien unter dem Titel Letters, Speeches and Addresses of August Belmont eine Zusammenstellung seiner Briefe und Reden. Nach Belmont, der ein begeisterter Sportanhänger war, ist das renommierte Pferderennen Belmont Stakes benannt. Ebenfalls nach ihm benannt wurde 1859 die Kleinstadt Belmont in New Hampshire eine Ehre, die er sein ganzes Leben lang nie anerkennen wollte. Die Figur des Julius Beaufort im Roman Zeit der Unschuld von Edith Wharton soll August Belmont nachempfunden sein.

Seine Söhne August (1851–1924), Perry (1851–1947) und Oliver (1858–1908) waren ebenfalls prominente Personen.

August Belmont, Sr. (1813-1890) was born in Alzey, Hesse, to a Jewish family. He immigrated to New York City in 1837 after becoming the American representative of the Rothschild family's banking house in Frankfurt. On receiving his American citizenship, he married Caroline Slidell Perry, daughter of Commodore Matthew Calbraith Perry.

August Belmont was born on December 8, 1813 (changed Schönberg to Belmont (German), to Simon and Frederika Elsass Schönberg. After his mother's death, when he was seven, he lived with his uncle and grandmother in Frankfurt. He attended the Jewish Junior and Senior High School until he began his first job, an apprentice for the Rothschilds. He would sweep floors, polish furniture, and run errands for the Rothschilds, while also studying English, arithmetic, and writing. He was then given a confidential clerkship in 1832 and promoted to private secretary before travelling to Naples, Paris, and Rome. In 1837, Belmont was assigned to Havana to manage the Rothschild's branches. However, while travelling to Havana, Belmont originally went to New York. He arrived during the Panic of 1837, and remained in New York instead of continuing on to Havana to supervise jeopardised Rothschild interests. He changed his surname to Belmont after emigrating to the United States.

In May 1837, right before Belmont (changed Schönberg to Belmont (German ) arrived in New York, nearly 250 businesses, including the Rothschild's American agents, had collapsed. As a result, Belmont postponed his Havana departure indefinitely and began August Belmont & Company, believing that he could replace the defunct American Agency with his company. It was an instant success, and Belmont was able to straighten out the Rothschild interests in the United States between 1837 and 1842. In 1844, Belmont was named the consul-general of Austria at New York in an attempt to strengthen his business position. He resigned in 1850 in response to what he viewed as Austria's cruel treatment of Hungary, and because of his increasing interest in politics.

After marrying Caroline Slidell Perry on November 7, 1849, (the daughter of Matthew Calbraith Perry ), his wife's uncle John Slidell became interested in Belmont, a Democrat unlike most of his business acquaintances, seeing him as an able and enthusiastic protégé. Belmont was originally asked by Slidell to campaign for James Buchanan in New York. Belmont began campaigning for him, and in June 1851, he wrote letters to the New York Herald and the New York National-Democrat, insisting that they do justice to Buchanan's presidential run. Although Franklin Pierce ended up winning the nomination, Belmont supported him and gave him large contributions despite being on the receiving end of political attacks. After Pierce's victory in the 1852 election, he appointed Belmont chargé d'affaires for the United States at the Hague, as well as the American minister at the same place due to his generous contributions to Pierce's campaign. During his time in Holland, Belmont encouraged his fellow diplomats James Buchanan and Pierre Soule to advocate American annexation of Cuba as a new slave state in the soon-notorious Ostend Manifesto.

Belmont's controversial stance on Cuba led Buchanan to deny him the ambassadorship to Spain, a position he lobbied for after Buchanan's 1856 electoral victory. As a delegate to the Democratic Convention of 1860, he supported Stephen A. Douglas, who subsequently named Belmont the Chairman of the Democratic National Committee the same year in Baltimore. He energetically supported the Union cause during the Civil War as a War Democrat, conspicuously helping Missouri Congressman Francis P. Blair raise and equip the Union Army's first predominately German-American regiment. Belmont also used his acumen with European business and political leaders on behalf of the Union Cause, dissuading the Rothschilds and many other bankers from providing the Confederates with loans, and meeting personally with the British Prime Minister Lord Palmerston and various members of Napoleon III’s French government.

Remaining chairman of the Democratic National Committee after the war, August Belmont oversaw the Party’s bids for power during what he called “‘the most disastrous epoch in the annals of the Democratic Party.’”He began his attempts to rally the disintegrating party as early as 1862, when he and Samuel Tilden bought stock in the New York World and shaped it into a major Democratic institution with the help of its editor, Manton M. Marble. Belmont, seeking to capitalize on Republican divisions at the war’s end, spent enormous effort organizing new party conventions and promoting Salmon Chase, whom he saw as the candidate least vulnerable to charges of disloyalty, for the 1868 Democratic nomination. Horatio Seymour’s eventual nomination and electoral defeat, while disheartening to Belmont, paled in comparison to Belmont’s humiliation by the Democrats’ 1872 nomination of Liberal Republican Horace Greeley for president. While the party chairman had promoted Charles Francis Adams for the nomination, Greeley’s nomination meant Democratic endorsement of a candidate who had frequently referred to Democrats, Irving Katz notes, as “‘slaveholders,’ ‘slave-whippers,’ ‘traitors,’ and ‘Copperheads,’ and frequently accused them of thievery, debauchery, corruption, and every known form of vulgarity and sin.” Although this embarrassment prompted Belmont to resign his chairmanship of the Democratic National Committee, he frequently reentered the political realm after 1872, as a champion of Delaware Senator Thomas F. Bayard as a presidential candidate, a fierce critic of the process granting Rutherford B. Hayes the presidency in 1877, and an advocate of “hard money.”

He died in New York in 1890 and a volume entitled Letters, Speeches and Addresses of August Belmont was published at New York in 1890. He left between 10 and 50 million dollars for his wife and children. He is now buried in Newport Rhode Island.

His sons Oliver Hazard Perry Belmont, Perry Belmont, and August Belmont, Jr. all rose to prominence in their own right.

He threw lavish balls, and dinner parties, receiving at times from New York's high society, at first, mixed reviews. An avid sportsman, the famed Belmont Stakes thoroughbred horse race is named in his honor. Its debut took place in Jerome Park Racetrack, where both he and track owner, Leonard Jerome competed with one another. Today The Belmont Stakes are part of the triple crown series, and is done at Belmont Racetrack in New York. Also named in his honor is the town of Belmont, New Hampshire - an honor Mr. Belmont never acknowledged. Also, Edith Wharton reputedly modeled her character of Julius Beaufort in Age of Innocence on August Belmont.