Battle of Chalchuapa

Since the end of Second Central American Civil War from 1838 to 1841, Costa Rica, El Salvador, Guatemala, Honduras, and Nicaragua existed as independent nations that were no longer political entities within the Federal Republic of Central America.^[3][4][5] During the Liberal Revolution of 30 April 1871, Divisional General Justo Rufino Barrios helped Divisional General Miguel García Granados rise to power and become President of Guatemala, ousting President Vicente Cerna y Cerna in the process.^[3][5][6][7] Barrios later became President in 1873 after García Granados retired.^[3] Barrios believed in Central American reunification and wanted to recreated a Central American union with himself as President.^[1] He was inspired by the unification of Germany under Prussia by Otto von Bismarck to unify Central America under Guatemalan with himself as President.^[5]

On 28 February 1885, Barrios proclaimed himself President of Central America and that he had supreme authority over every nation of Central America.^[3][5] The National Assembly of Guatemala approved Barrios' declaration during a meeting on 5 March.^[3][7] Barrios believed the other Central American nations would join his union, but only Honduras approved of Barrios' declaration which they approved on 7 March.^[1][3] Costa Rica, El Salvador, and Nicaragua all denounced the declaration.^[1][3] Barrios mobilized the Guatemalan Army on 10 March in preparation to form his union by force and war began on the afternoon of 29 March 1885.^[1][7] Barrios thought that the threat of force would make El Salvador submit, but he was notified that Salvadoran President Rafael Zaldívar was assembling his own army to defend against the Guatemalans.^[1]