Born in Cochambamba, Salamanca studied law, before being elected to Bolivia's Chamber of Deputies in 1899 for the Liberal Party. Two years later, President José Manuel Pando appointed him Finance Minister. Salamanca eventually split with the liberals, however, and helped to found the new Republican Party, running unsuccessfully for vice president in 1917 and for president in 1920 against fellow Republican Party member Juan Batista Saavedra.
Shaken by his two defeats, he retired from politics and taught law instead, until the overthrow of Hernando Siles as a result of the Great Depression in 1929. Asked to head a Republican-Liberal coalition, Salamanca led the party to victory and took office in 1931.
Immediately upon assuming office, Salamanca introduced an unpopular austerity program and clamped down on political opposition to his government. In what was likely a measure to avert public attention to the economic problems still facing the country, he also revived hostilities with Paraguay in the disputed Chaco region, ordering the army to attack a Bolivian garrison at Vanguardia. This ignited the disastrous Chaco War (1932-1935). The war only exacerbated already severe economic problems in Bolivia (and in Paraguay), while causing many thousands of casualties. On November 27, 1934, a group of Bolivian generals deposed Salamanca while he visited their headquarters Villamontes and replaced him with the vice president, José Luis Tejada Sorzano. Salamanca retired to Cochabamba, where he died less than a year later.