The Greek Civil War
The Greek Civil War quickly turned into one of the strangest Cold War proxy wars, emblematic of the cynical power politics of the Cold War. After British troops withdrew from Greece in 1947...they were in turn not replaced by anyone. In contrast, Yugoslav troops and supplies flooded into Northern Greece, aiding the Democratic Army of Greece. However, the entire war got caught up not in the Soviet-American split of 1948, but rather the simultaneously Informbiro crisis and Tito-Stalin split. With Tito purging Stalinists and Stalin purging Titoists, the Greek Communists had a difficult decision to make - whether to side with Tito or Stalin. By 1948, the Greek Communists clearly had the upper hand, with Northern Greece completely lost to the Communists as the Royalists had already lost almost all meaningful control in the North and were fighting a desperately losing defense across Roumeli (Central Greece). Unwilling to jeopardize what had clearly been an incredibly successful partnership, the Greek Communist Party made their choice - they would stand with Tito and continue receiving his support. Without foreign support, the Royalists were resigned to trying to build a bulwark in Attica, even worse, the Peloponnese, or even in the worst-case scenario, Crete.
In 1948 however, their savior had emerged - military aid from the most unexpected of sources. Stalin, still fuming from the "betrayal" of the Communist Party of Greece (who the Soviet Union had never actually aided), decided to make his play. Soviet arms, shipping through the Turkish Straits (intentionally let through by the Turks, under the 1946 Wallace-Stalin Turkish Straits agreement that gave power to veto military transfers solely to Turkey and the USSR), went directly to the Greek Royalists. In a sharp irony, the fiercest anti-communists of Greece were bankrolled...by the Soviet Union. In particular, they deeply funded the controversial far-right paramilitary, Organization X under Georgios Grivas, notorious in Greece for their participation in right-wing death squads during the 1945 White Terror. Stalin himself commented that Grivas had killed more Titoists than any man alive not named Stalin and thus he had earned Soviet support. Upon hearing of Soviet aid to the Royalists, one of President Wallace's last acts in office was to greenlight immediate American aid towards Yugoslavia and the Greek Communists. The Greek Civil War rapidly expanded in violence and destruction, as hundreds of thousands would flee the country as refugees, primarily to Crete and most disturbingly to British authorities, Cyprus. Winston Churchill's first act as Prime Minister was out of genuine humanitarian concern for Greece, open up Cyprus to Greek refugees, an act which would have significant ramifications for Britain.
The Soviets generally expected the Royalists to lose, which was why Stalin was supporting them. The Soviets didn't actually want to sponsor an anticommunist government, but they correctly realized that by funding the Royalists, they could force the Yugoslavs and "Greek Titoists" to bleed. The Turks had cooperated simply because Turkey was horrified at the notion of having a second Communist neighbor, and they had generally believed the Royalists would also lose. Interestingly, the Soviets of course were never going to openly fund the Royalist Greeks; although the Americans and British knew that the Soviets were bankrolling the Royalists, most Greeks did not. Instead, arms shipments to the Royalists were generally disguised as from Turkey, which created an interesting amount of goodwill between the Greek Royalists and the Turks. Moreover, neither Turkey nor the Soviet Union had expected the Royalists to fight so ferociously. As the Greek Communists refused to compromise on key issues like the status of the Orthodox Church, Greek peasants flocked to fight for the plucky Royalists, ferociously resisting the Communists. In Moscow, Stalin continued to fume, eventually suggesting to his cabinet that something would have to be done about the "Titoist cancer."