While in the army commanded by Urquiza, he writes the Boletín del Ejército Grande (Great Army bulletin) and participates in the Battle of Caseros (1852). He returns to Chile and the debate, this time with Juan B. Alberdi, the author of Las Bases (Foundations and starting points for the political organization of the Argentine Republic). He settles in Buenos Aires (1855), where he resumes his journalistic activity, becomes a member to the Municipal Council, and is appointed Head of the Schools Department. As a senator, he submits several projects regarding public education and agrarian law.

He takes part in the National Constitutional Convention (1860); he is later elected governor for San Juan, where he makes a vast contribution to government. He is appointed Minister Plenipotentiary to the United States (1865–68), a country he travels and eagerly explores throughout. A presidential candidate in Argentina, he is appointed by the Legislative Assembly and takes office on October 12, 1868.

His administration reveals the multifaceted statesman he was. He conducts the first National Census (1869), fosters immigration, has the Vélez Sarsfield's Civil Code passed, appoints Benjamín Gould as director of the Astronomical Observatory of Córdoba, opens new railroad lines, and introduces the telegraph and the submarine cable. Furthermore, he builds roads, nationalizes the postal system, introduces the metric system, and promotes the creation of new industries and the colonization of fields. He founds the National Bank, the Department of Agriculture, the Military School, and the Naval School. He adopts a law to establish public libraries, supports the Museum of Natural Sciences (in Buenos Aires) and the Academy of Sciences (in Córdoba), hires foreign scientists and pedagogues, and has the decree on provincial school subsidies passed.

When his term of office comes to an end, he is succeeded by Nicolás Avellaneda. Sarmiento oversees work at Tres de Febrero park, takes office once again as the head of the General School Bureau, opens educational institutions, and later supports the Pedagogical Congress. He publishes Conflictos y armonías de las razas en América (Conflict and harmony among American races) -1883-. Congress approves the publication of his Obras completas (Complete works) -1884-. He moves to Paraguay in 1887, where he dies the following year; his tombstone bears the following epitaph, which he himself wrote: "A whole America home to all gods, with free tongue, land, and rivers for everyone."

Sarmiento discovers his vocation for teaching at the early age of fifteen. Together with José de Oro, his uncle and a teacher as well, he teaches rural people in a humble hut in San Francisco del Monte, in the province of San Luis.

The main motifs are intaglio printed and the background is offset printed.

The center front features his portrait and the background, a reproduction of Vida de Dominguito (Little Domingo's life), a biography of his foster son killed in the Battle of Curupaytí (September 22, 1866).

The main motifs are intaglio printed and the background is offset printed.

The back portrays the Government House, the seat of the Executive branch of government, located at the Customs building in 1862, the former headquarters for the Buenos Aires Fort. It is reformed and enlarged in 1867 under the supervision of architect José Canale. Under Sarmiento's orders, the garden and the iron gate in the northern side are built and the whole building is painted pink, which is the reason why the Government House is known as the Pink House (1870). That year, the Post Office building is built in the southern wing. During Julio A. Roca's administration (1882), the Post Office is moved out to a new building; the two wings, joined by a bridge, define the current aspect, Italianizing in style due to Francisco Tamburini's inspiration.

It also features a summary of the national hero's biography in microprinting and motifs evoking his various activities:
- Railways, on August 30, 1857, the first Argentine railway line is inaugurated. The first locomotive to provide travel this line is "La Porteña," built in England, that goes from the Park (now Lavalle Square) to Floresta and back. During Sarmiento's term of office, railway lines grow from approximately 355 to 826 miles, a major achievement in his communications policy.
- Immigration, Sarmiento highlights the importance of the immigrants' contribution in the intellectual sphere; thus, he takes measures to triple the immigrant inflow of the previous six years.
- Writing and journalism, he publishes his masterpiece Facundo. Civilización y barbarie. (Facundo. Civilization and barbarism) in El Progreso newspaper (Chile).