It is commonly assumed that Spain fought a civil war from 1936 to 1939. However, Spain’s civil war only lasted a few days following the Franco coup of July 18. The original plan of the coup was defeated throughout Spain within ten days, leaving the Nationalists in a precarious position. They held less than half of Spain and were faced by an armed populace eager to make a revolution. Once Germany and Italy began to supply Franco, the result was the transformation of the Spanish Civil War into an international war.
What exactly was the initial plan of the Nationalists gathered around Franco? “[The plan] envisioned a simultaneous rising in all the areas of the country, beginning with the proclaimation of a ‘State of War.’ The first and immediate objective would be to paralyze all possible resistance, occupy all strategic points, etc.” What happened next was that in eight days, the Nationalists secured control of Morocco and vast tracts of central Spain. Their territory was split into two halves, separated by hundreds of miles. The Army of Africa, the best troops in Spain were stationed in Morocco with no way to reach the mainland (the bulk of the navy remained loyal). If the Army of Africa was unable to reach the mainland, the bulk of Nationalist forces would be isolated. It was the German airlift (mostly Junker 52s) and naval assistance (these ships were vastly superior to antiquated Republican vessels) that allowed for Franco to move his elite troops and weapons to the mainland. Once the Army of Africa crossed over to the mainland, they were able to make mincemeat of Republican forces (thanks also to foreign aid).
The Nationalist uprising failed on the mainland for one major reason. When the workers and peasants got arms, they attacked the Nationalists and generally defeated them. The Republican government in Madrid often hesitated in giving arms to the workers, which would allow for the Nationalists to sweep in and seize areas. It was the armed workers who secured Madrid, Barcelona and other vital regions for the Republic. It was this act which prevented the Nationalists from securing the mainland. The workers and peasants did not just defeat the rising throughout Spain, they formed their own military units and began a revolutionary transformation in Spain. The workers and peasants were fighting not just for the Popular Front, but for a revolution. The Nationalists were facing more than a timid Popular Front, they were up against a people eager for revolution.
What the Republic needed to defeat the rising, once the Nationalists had landed the Army of Africa on the mainland, was arms. The Nationalists had the bulk of the military on their side and some of the best units (Army of Africa) along with significant foreign aid. The Republic needed aid from the outside for their army, but it was not forthcoming. Great Britain and France (by in large) did not provide weapons to the Republic. The French closed their border (except for a few brief instances) to weapons which had been purchased by the Republic. It was only the Soviet Union (to a lesser extent Mexico) which gave the Republic any sort of major weapons, although they often had trouble arriving in Spain. Britain and France did not just deny the Republic arms, they also colluded with the Nationalists in securing safety for German/Italian supplies and stopping Republican arms shipments. Britain and France were also involved in the Non-Intervention Committee, which was supposed to keep foreign weapons from reaching Spain. However, in patrolling the Spanish coast, the German and Italian navies also participated (the two biggest violators of non-intervention).
The Spanish Civil War was only an internal military coup in the first eight days, after that Germany and Italy began to airlift Nationalist troops to the mainland. A Civil War implies that there are two sides of equal validity and claim to a country. In Spain, the Nationalists represent capitalism, fascism, and the assorted scum of reaction (a limited popular base). The Republic, especially after the coup was being defended by the revolutionary masses (the workers and peasants). Once Germany and Italy (with the tacit collaboration of the UK and France) threw their weight behind Franco, the Soviet Union responded by aiding the Republic. This turned the Spanish Civil War into an International War.
 Arthur H. Landis, Spain: The Unfinished Revolution (New York: International Publishers, 1972), 85. See also Antony Beevor, The Battle of Spain (New York: Penguin Books, 2006), 55.
 See Beevor, 2006, 64 for the Army of Africa needing German aircraft to reach the mainland. For the role of the navy and the defeat of the coup on Spanish ships, see ibid. 71-4.
 Hitler remarked ‘that Franco should erect a monument to the plane because it was so vital to his victory.’ Ibid. 73.
 For the advance to Madrid by the Army of Africa see ibid. 116-123. In August of 1936, Italy sent Franco a minimum of 27 fighters, 5 tanks, and forty machine guns. Up to September 1936, Germany and Italy sent a combined total of 129 aircraft sent to Franco. The USSR only began its supply of the Republic in October 1936. See Michael Alpert, A New International History of the Spanish Civil War (New York: Palgrave, 2004), 47 and 78. For an excellent summary of foreign aid to all sides see Thomas, 2001, 934-44.
 Landis, 1972, 165.
 For the initial hesitancy of the government see Beevor, 2006, 55.
 Hugh Thomas, The Spanish Civil War (New York: Modern Library, 2001), 208-19 and 221-5.
 For a description of the Republican zone right after the coup see Beevor, 2006, 102-114.
 The Italians sent at least 70,000 troops and the Germans often provided some of their best fighters for the air force and outperformed Soviet fighters. Stanley G. Payne, The Franco Regime (Madison: University of Wisconsin Press, 1987), 156-160. It would be air cover that would prove decisive in the defeat of the Republic at the Battle of Ebro in 1938 for instance, see Beevor, 2006, 352-6.
 The Comintern also organized the International Brigades which brought at least 35,000 troops to aid the Republic from 53 nations. These soldiers proved invaluable during the Battle of Madrid in 1936 and stayed in Spain until late 1938. For a brief overview of the Brigades see Thomas, 2001, 940-4.
 Robert Colodny, Spain: The Glory and the Tragedy (New York: Humanities Press, 1970), 26-36. See ibid. 48 for the hostile Mediterranean route of Soviet arms to the Republic. Also Payne, 1987, 158 for a list of Soviet aid to the Republic.
 Landis, 1972, 192-204.
 Francisco J. Romero Salvado, The Spanish Civil War (New York: Palgrave, 2005), 153.