Since the 19th century, relations between Argentina and Britain had been strong due to trade, as well as British investments and immigration. Nationalistic groups resented this influence over Argentina's economy.Senkam, Leonardo (1995). El nacionalismo y el campo liberal argentinos ante el neutralismo: 1939–1943, Estudios Interdisciplinarios de América Latina y el Caribe, Vol. 6 Nº 1, ene-jun 1995, Universidad de Tel Aviv In the interwar years, fascist Italian and German influence in the country increased due to trade, investment, and the presence of numerous immigrants from both countries.

The refusal to break relations with the Axis powers as the war progressed furthered the belief that Argentina was sympathetic to them. Because of strong divisions and internal disputes within the Argentine military, Argentina remained neutral for most of World War II, despite pressure from the United States to join the Allies.Galasso, 117–252 Argentina eventually gave in to the Allies' pressure, breaking relations with the Axis on 26 January 1944Galasso, pp. 194–196 and declaring war on them on 27 March 1945.Galasso, pp. 248–251

The Nazis had a presence in the country as early as 1925, growing to a peak of 2,110 party members in 1935 before officially dissolving in 1939. Afterwards, Buenos Aires was a major center of Axis espionage under the guise of German labor organizations and with support from the United Officers' Group. Argentine, Chilean, and U.S. agencies shut down some local spy networks, but activity occurred as late as 1950 under Juan Perón, allowing perhaps 5,000 collaborators to escape there.

Pre-war political and economic background

19th century–World War I Argentina maintained a long tradition of neutrality regarding European wars, upheld and defended by all major political parties since the 19th century. One of the main reasons for this policy was related to Argentina's economic position as one of the world's leading exporters of foodstuffs and agricultural products, to Europe in general and to the United Kingdom in particular.

Relations between Britain and Argentina had been strong since the mid-19th century, due to the large volume of trade between both countries, the major presence of British investments particularly in railroads and banking, as well as British immigration, and the policy of neutrality had ensured the food supply of Britain during World War I against the German U-boat campaign.Allén Lascano, Luís C. (1977). Argentina y la gran guerra, Cuaderno 12. «La Soberanía», Todo es Historia, Buenos Aires, pags. 71–113

Before the Great Depression In 1916, following the enactment of universal and secret male suffrage by conservative president Roque Saenz Peña, the voting franchise was expanded, and electoral transparency improved, leading to the first truly free presidential elections in the country. As a result of these electoral changes, Hipólito Yrigoyen, leader of the centrist Radical Civic Union (UCR), was elected President of Argentina. Under the successive administrations of presidents Yrigoyen (1916–1922) and Marcelo Torcuato de Alvear (1922–1928), Argentina continued the trend of strong economic growth and democratic consolidation that had begun under previous administrations, matching countries such as Canada or Australia in per capita income, while the government enacted social and economic reforms and extended assistance to small farms and businesses. Beginning in 1928, Yrigoyen's second administration faced a crippling economic crisis, precipitated by the Great Depression (1929–1939).

1930 military coup In 1930, Yrigoyen was ousted from power by the military led by José Félix Uriburu, in what became the first military coup in modern Argentine history, marking the beginning of what would be later called the Infamous Decade in Argentina.

Supported by nationalistic sectors of the military, Uriburu tried to implement major changes to Argentine politics and government, banning political parties and suspending both elections and the 1853 Constitution, aiming to reorganizing Argentina along corporatist and fascist lines. However, Uriburu's policies would face widespread opposition from civil society and from conservative factions of the military, and only a year later, in 1931, he was forced to step down. Thus, in November 1931, the military government called for elections, but only after banning UCR candidates and organizing a system that was broadly recognized as fraudulent. It was under these conditions that General Agustín P. Justo was elected president.Michael A. Burdick. For God and the fatherland: religion and politics in Argentina. Albany, New York, USA: State University of New York Press, 1995. p. 45.Daniel K. Lewis. The history of Argentina. 2nd edition. New York, New York, USA; Hampshire, England, UK: Palgrave Macmillan, 2003. pp. 83–84.

Presidency of Agustín P. Justo

Elected on 8 November 1931, Justo was supported by a newly created conservative party known as Concordancia, which was born as an alliance between the National Democratic Party, dissident sectors of the Radical Civic Union that had opposed Hipólito Yrigoyen, and the Independent Socialist Party. Still reeling from the aftermath of the Great Depression, Justo's government at first undertook fiscally conservative economic policies, reducing public expenditure and restricting the circulation of currency in an attempt to strengthen the public coffers. However, as in other countries during this period, Keynesian ideas were eventually implemented, and more emphasis was placed on public works and infrastructure, resulting in the creation of the National Office of Public Highways, expansion of the road network, creation of the Junta Nacional de Granos (National Grain Board) and the Junta Nacional de Carnes (National Meat Board), and, in 1935, creation of the Central Bank of the Argentine Republic, under the advice of economist Otto Niemeyer.

In foreign policy, the most pressing issue of the Justo administration was the restoration of international trade, which had collapsed following the Great Depression. As a byproduct of Black Tuesday and the Wall Street crash of 1929, Great Britain, principal economic partner of Argentina in the 1920s and 1930s, had taken measures to protect the meat supply market in the Commonwealth. At the 1932 Imperial Conference negotiations in Ottawa, bowing to pressure, mainly from Australia and South Africa, Britain had decided to severely curtail imports of Argentine beef. The plan provoked an immediate outcry in Buenos Aires, and the Argentine government dispatched Vice President Julio Argentino Pascual Roca and a team of negotiators to London. As a result of these negotiations, on 1 May 1933, the bilateral treaty known as the Roca–Runciman Treaty was signed between Argentina and the United Kingdom, which guaranteed Argentina a beef export quota that was equivalent to the levels sold in 1932, in exchange for Argentina reducing tariffs on almost 350 British goods to 1930 rates and to refrain from imposing duties on coal, strengthening the commercial ties between Argentina and Britain and ensuring a trade surplus during the turmoil of the Great Depression, but drawing ire from nationalistic sectors and several opposition senators, including the denunciations of liberal Senator Lisandro de la Torre, who claimed that Britain received the most benefits from the treaty. Ratified by the Argentine Senate, the Roca–Runciman Treaty lasted three years and was renewed for another three years as the Eden-Malbrán Treaty of 1936. Argentina under Justo would also rejoin the League of Nations, and hold state visits to presidents Getúlio Vargas of Brazil and Gabriel Terra of Uruguay, signing commercial treaties with those nations. Justo's foreign minister, Carlos Saavedra Lamas would also serve an important role as a mediator in the Chaco War between Bolivia and Paraguay, helping both countries reach a peace deal, thus winning the 1936 Nobel Peace Prize.

Mounting political tensions In the aftermath of the 1930 military coup and the subsequent accusations of electoral fraud against Justo, political tensions in Argentina would remain high throughout the 1930s. On 5 April 1931, supporters of deposed president Yrigoyen won the elections for governor in Buenos Aires Province, but the government of Uriburu declared the elections invalid. On December, facing uprisings by UCR supporters, Justo decreed a state of siege, and again imprisoned the old Yrigoyen, as well as Alvear, Ricardo Rojas, Honorio Pueyrredón, and other leading figures of the party.

In 1933, attempted revolts continued. The provinces of Buenos Aires, Corrientes, Entre Ríos, and Misiones would be the stage of UCR uprisings, which ended with more than a thousand people being detained. Seriously ill, Yrigoyen was returned to Buenos Aires and kept under house arrest. He died on 3 June, and his burial in La Recoleta Cemetery was the occasion of a mass demonstration. In December, during a meeting of the national convention of the UCR, a joint uprising by the military and politicians broke loose in Santa Fe, Rosario, and Paso de los Libres. José Benjamin Abalos, who was Yrigoyen's former Minister, and Colonel Roberto Bosch were arrested during the uprising and the organizers and leaders of the party were imprisoned at Martín García. Former President Marcelo Torcuato de Alvear was exiled by the government, while others were detained in the penitentiary in Ushuaia.

In 1935, Alvear was allowed to return from exile as part of a gentlemen's agreement with Justo, with Alvear promising there would be no more violent rebellions in exchange for Justo promising an end to fraudulent elections. Thus Alvear took on leadership of the UCR party, vowing that the UCR would once again take part in elections and to continue the fight against fraudulent practices. That same year, once again amid accusations of fraud, the Justo administration managed to secure the victory of its candidate Manuel Fresco for governor of Buenos Aires Province, but it could not avoid the UCR victory of Amadeo Sabattini for governor in Córdoba, despite bloody incidents that aimed at disrupting the election. Meanwhile, the province of Santa Fe, under the leadership of opposition Democratic Progressive Party governor Luciano Molinas, was the subject of a federal intervention by the national government.

In 1937, presidential elections were to be held. Alvear, together with his running mate Enrique Mosca campaigned across the country, vowing that "not even fraud could defeat them". Meanwhile, the ruling Concordancia party, nominated lawyer Roberto Marcelino Ortiz, from the dissident anti-Yrigoyen UCR faction, as presidential candidate, with conservative lawmaker Ramón Castillo, as his running mate. The 1937 presidential elections were held in September. Completely flouting on his promise, Justo kept his political and security forces busy on election day. Amid widespread reports of intimidation, ballot stuffing and voter roll tampering (whereby, according to one observer, "democracy was extended to the hereafter"), Ortiz won the elections handily.Todo Argentina: Fraude Patriotico

Beginning of the war Political situation