In 1929, Argentina had the world's fourth highest per capita GDP. These years of prosperity ended with the Crash of 1929 and the ensuing worldwide Great Depression. In 1930, a military coup, supported by the Argentine Patriotic League, forced Hipólito Yrigoyen from power, and replaced him by José Félix Uriburu. Support for the coup was bolstered by the sagging Argentine economy, as well as a string of bomb attacks and shootings involving radical anarchists, which alienated moderate elements of Argentine society and angered the conservative right, which had long been agitating for decisive action by the military forces.
The military coup initiated the period known as the "Infamous Decade", characterised by electoral fraud, persecution of the political opposition (mainly against the UCR) and pervasive government corruption, against the background of the global depression.
The Roca-Runciman Treaty passed between Argentina and the United Kingdom, which favored the British economy, was strongly denounced by the leftist FORJA, headed by Arturo Jauretche and other opponents to Marcelo Alvear's decision, in 1934, to end with the UCR's absentionist stance towards Agustín Pedro Justo's military regime (1932–1938).
The collapse of international trade led to industrial growth focused on import substitution, leading to a stronger economic independence. Political conflict increased, marked by confrontation between right-wing fascists and leftist radicals, while military-oriented conservatives controlled the government. Though many claimed the polls to be fraudulent, Roberto Ortiz was elected president in 1937 and took office the next year, but due to his fragile health he was succeeded by his vice-president, Ramón Castillo. Castillo effectively took power in 1940; he formally assumed leadership in 1942.