Short answers, pulled from the story.
The Axis occupation of Greece began on the 28th of October 1940 when Italian forces invaded after Greek premier Ioannis Metaxas rejected their ultimatum. German troops entered northern Greece on the 6th of April 1941, and by the 1st of June all of Greece was under Axis control following the capture of Crete.
Some 40,000 people died of starvation in the greater Athens-Piraeus area alone during the winter of 1941-42. Estimates suggest the total population of Greece was 300,000 less than it should have been due to famine or malnutrition by the time the occupation ended.
The National Liberation Front (EAM) was established on the 27th of September 1941 with its military wing called ELAS under Aris Velouchiotis. By September 1943, ELAS strength reached about 15,000 fighters with 20,000 reserves while another group EDES operated primarily in Epirus under Napoleon Zervas.
Mass deportations began in March 1943 sending Jews of Thessaloniki and Thrace in packed boxcars to Auschwitz and Treblinka death camps. At least 81% of Greece's total pre-war Jewish population perished, with only 1950 individuals surviving from Thessaloniki's community.
Greece's territory was divided into three distinct occupation zones run by Germany, Italy, and Bulgaria each with different administrative strategies. The German zone included Athens and Thessaloniki while the Italian zone covered most of the mainland including Epirus and the Peloponnese until Italy surrendered in September 1943.