The significance of foreign intervention in influencing the outcome of the Spanish Civil War cannot be overstated enough by historians. Several have unanimously agreed that it considerably lengthened and intensified the war while ensuring that Spain’s domestic issues were overtaken and submerged by the more significant ideological battles that were taking place in Europe. Of these foreign powers, a few stand out significantly for their role in exacerbating the conflict and causing a polarised European continent in the lead-up to the Second World War in 1939. Countries such as Britain, France, USSR, Italy, Germany and Portugal were particularly notable in terms of their contributions, both monetarily and militarily.
Foreign intervention in the Spanish Civil War was primarily significant because of the military advantages it granted the Nationalists with. Historian Hugh Thomas concurs and goes so far as to say that the conflict’s final solution “was determined by external circumstances”, underscoring the extent of the military contribution to the war’s outcome. Portugal, Germany and Italy specifically provided military aid to the nationalists to prevent the spread of communism within Europe and empower the nationalist regime, which would serve as an ally. Portugal sent nearly 20,000 troops, which proved vital to supplying the rebels along the “Spanish-Portuguese border” and providing a base for communications. Germany contributed to the effort by airlifting 24,000 nationalist troops into Spain at the beginning of the war; these “Africanistas” were the best troops of the Spanish Army; the airlift gave the Nationalists an advantage by allowing them to hinder Republican efforts to put down a rebellion on the mainland. Moreover, German contribution to air warfare also proved crucial to tilting the war’s outcome in favour of the Nationalists. In April 1937, Germany provided the Nationalists with the Messerschmitt, a set of 109 planes equipped with the newest combat technology. These planes helped Franco, the Nationalist commander, gain air superiority over the Republican forces. It also enabled the nationalists to cut the republican territory in half in 1937 and assisted in destroying Basque resistance through heavy bombing campaigns such as those in Guernica and Bilbao. This assistance critically weakened the republicans. On the other hand, Hitler also sought to benefit from this contribution as it gave his forces time to test much of the equipment and military technology that would be used in the event of a Second World War, the threat of which was looming large by 1937.
Foreign intervention also provided the Nationalists with a strong economic advantage. During the conflict, Portugal, which was supporting the Nationalists, acted as a “safe haven for supplies to be transported across its border to the nationalists”. Despite the existence of a non-intervention committee (led by Britain and ratified by countries such as Germany, Italy & USSR), Britain also took several less prominent actions that favoured the nationalists, likely once again due to a fear of spread of communism over facism. Britain, for instance, signed an agreement with the nationalist government in December 1936 that allowed British companies to trade with it. It also permitted the nationalists to use Gibraltar as a communications base between Franco’s forces, Italy and Germany. The nationalists also were able to acquire some 700 million US dollars in loans from the ‘neutral’ USA that were used to purchase key war material like rubber and oil form US companies such as Texaco and general motors. This economic assistance from foreign powers allowed the nationalists to fund and supply their war effort and ultimately was crucial in its victory in the war.
While it is increasingly evident to historians that foreign intervention on the Nationalist side was extremely beneficial, several have argued the converse for the foreign intervention on the Republican Side; the only power to aide the Republicans during the war was the USSR, which provided approximately 1000 aircrafts and 750 tanks but no manpower. The Soviet support for the Republicans, it appeared, was exceptionally insignificant in comparison with their Nationalist counterparts. The USSR also provided the “International Brigades” to aid the Republican cause. Yet, the troops were poorly trained and the support was insufficient to impact the military reality on the ground. Furthermore, the USSR’s aide also arguably caused intra-party hostility, weakening the Republicans significantly; the limited aid granted by the USSR was particularly exploited by the communist factions of the Republican party greatly, who used this to their advantage to grow in size. Other parties who identified with the Republican cause but not necessarily with communism began to grow increasingly resentful about this misallocation of Soviet funds. Over time, some historians have put forth the argument that given that the USSR was the only power to aid the Republicans, eventually this created an image of Republican forces being dominated by communists. Moreover, Stalin’s agents’ participation within the conflict effectively eliminated any likelihood of other countries pitching in to support the Republicans, for fear of communism spreading further. To make matters worse, by 1938 the Soviets and the international brigade withdrew from the war, sealing the fate of the Republic, effectively paving the way for the Nationalist victory in 1936.
In essence, during the Spanish Civil War, foreign intervention, coupled with the effective administrative strategies of the Nationalists allowed for a decisive victory in 1936. The war, after 1936, exposed the inherent weaknesses of the Republican Side and exacerbated its political divisions and military inexperience.