As the Soviet's began pushing back the Germans in World War II they eventually were able to take control of countries in Eastern Europe. These countries would eventually all become puppet states or part of the USSR. Why didn't Greece fall under Soviet control and how did it resist Socialism? Surely the 'birthplace of Democracy' would have been an excellent prize and propaganda tool for the Soviets.
The short version is that Greece did not become of the Soviet bloc because Stalin kept his agreements with the Western Allies.
According to legend spread by Churchill, at the Moscow conference in 1944, he and Stalin divided up Europe by percentage. According to him, Stalin and he did that on a paper napkin. Churchill even went so far as to publish his secret "percentage agreement" after the war.
While it is a good story, a lot of it is the stuff of legend. The day after this happened, Stalin got a memorandum of the meeting and was careful to remove all references to spheres of influences and percentages. While the percentage thing was probably the stuff of legend, there was nonetheless an agreement between the USSR and the West that Greece would be in the Western sphere of influence while the USSR would get free political passages in other countries.
That Stalin kept to this agreement and that it was to him and the regime of the USSR politically unfeasible to integrate Greece in their sphere of influence is obvious from the post-war situation in Greece. Greece during the Axis occupation presents a picture similar to that in Yugoslavia, most notably by being a civil war inside a war of liberation.
With the Greek government in exile from the Axis invasion 1941 onward, a variety of political liberation movements formed in Greece during the war, most prominent the National Liberation Front (EAM), and its military branch the Greek People's Liberation Army (ELAS); both being communists and effectively run by the Greek Communist Party (KKE). Another, though smaller, non-communist resistance organization was the National Republican Greek League (EDES).
In 1943, with the Axis encountering major problems and with Italy dropping out of the war, a rift between EAM/ELAS and the other resistance organizations erupted, mainly concering the political future of Greece (Socialist Republic vs. Republic vs. Kingdom), over accusations of collaboration leveled by EAM at EDES and because of British support for virtually all resistance organizations except the biggest one, EAM/ELAS. As mark Mazower wrote in Inside Hitler's Greece:
As potential allies for the British in an anti-communist crusade the Germans and the Security Battalions were obviously less politically palatable than ELAS's resistance rivals, even though these incresingly powerless and confirmed to the area of Athens. As well as contacting the GFP [Geheime Feldpolizei – the Wehrmacht's political police], Stott [the British Secret Service representative in Greece] had alos met representatives of all the Greek resistance organizations except EAM/ELAS to discuss how British arms could be supplied to them. These contacts, unlike those with the Germans were carefully maintained, chiefly through the Greek governemnt in exile, in the months leading up to Liberation, by which time the non-communist resistance was being seen as an essential buffer against the Left.
By 1944, hostility to EAM/ELAS had pushed several of these right-wing "resistance" groups closer to the Security Battalions and their German sponsors. Here we find ourselves in the murky atmospehere of underground "nationalist" politics, a highly duplicitous and dangerous world, where resistance did not rule out collaboration, and where service alongside the Wehrmacht was justified on the grounds that it was necessary to save Greece from the Left. In Athens, for example, members of EDES enlisted in the Battalions, while several prominent leading EDES officals cultivated close ties with the [collaborationist] Rallis government.
The hostility between EAM/ELAS and the British supported other resistance organizations as well as collaborationist police agencies was not over when Liberation came but actually got worse. Take the happenings of December 3, 1944, two months after the Germans had retreated from Greece. On that day, Greek government gendarmes opened fire on an unarmed EAM demonstration with British troops watching on. Similarly, in the streets of Athens EAM/ELAS troops actually fought with British troops over control of the city when the British army came to drive the Germans back.
In 1946 civil war erupted openly. Unlike Yugoslavia where the resistance was strong enough to quickly establish supremacy and also did not face rivals supported by the Western Allies, in Greece that was not the case. Additionally, the Soviet Government denied the EAM/ELAS and the KKE all support, practically as well as politically. In the following three years of Civil War, the only force supporting the EAM/ELAS was actually Yugoslavia, explicitly against Stalin's wishes.When Yugoslavia ceased its support under Soviet pressure in 1949, the KKE and its troops lost the war and left Greek society deeply divided for years on – so much so that in the late 1960s the military orchestrated a coup d'etat against a moderate left-wing government for fear of communism returning.
That the Soviet Union was opposed to support for the Greek communists can be gleaned from a meeting they had with the Yugoslavs in the Kremlin in 1948 where Stalin explained that the situation in Greece has always been different from the one in Yugoslavia because the US and Britain would "never permit [Greece] to break off their lines of communication in the Mediterranean".
So, in short, the reason Greece did not become socialist was the the Soviet Union didn't regard support for the quite large and popular communist movement as politically feasible while the Western Allies, including the US and Britain massively backed former collaborators and political rivals of EAM/ELAS to prevent the communists from gaining power either by violence or democratic means.
