On 28 October 1940, Italy began the Italo-Greek War, expecting a swift victory but the invasion failed and the Italians were pushed back into Albania.

Unlike Italy and Germany, Bulgaria did not administer Eastern Macedonia and Thrace through Greek collaborators but annexed the area to form the province of Belomorie.

The group was short lived as internal political disagreements and the work of Axis intelligence services suppressed its activities and bands belonging to the communist-led Greek People's Liberation Army (ELAS), became the dominant resistance organization in the country.

[1] In June 1943, the head of the British Special Operations Executive mission in Greece, Brigadier Eddie Myers, conceived the Agreement of National Groups.

British planners considered that an invasion of France from Britain could not take place until 1944, and the Prime Minister, Winston Churchill, wanted to use the Allied forces from North Africa to attack Europe's "soft underbelly".

[4][5][n 1] At the Casablanca Conference in January 1943 Allied planners agreed on the selection of Sicily – codenamed Operation Husky – and decided to undertake the invasion no later than July that year.

[8] Adolf Hitler was concerned about a Balkan invasion, as the area had been the source of raw materials for the German war industry, including copper, bauxite, chrome and oil.

[10] To suggest the eastern Mediterranean was the target, the Allies set up a headquarters in Cairo, Egypt, for a fictional formation, the Twelfth Army, consisting of twelve divisions.

[11][12] On 29 May, Myers was informed by Cairo that Sicily was to be invaded in the second week of July and ordered that Greek resistance organizations were to commence Operation Animals a sabotage campaign throughout Greece.

On the night of 1 June, an ELAS engineer unit, accompanied by 250 fighters, blew up the tunnel while a train loaded with ammunition and Italian soldiers on leave was passing through.

On 20 June, in 'Operation Washing', a group of six SOE officers evaded German guards to scale a steep slope near the Asopos bridge, place explosives at its northern end and set them off.

Upon hearing about the demolition, Adolf Hitler expressed his dissatisfaction with the level of protection of the Greek railroad network, while also acknowledging that such subversive acts could not be wholly avoided.

Animals then began in Macedonia; the Germans reinforced their garrisons and arrested hundreds of civilians and forced them to lift mines on the railroads, under threat of death.

After the departure of the Mountain Division towards Ioannina, the area was declared a dead zone and placed under the control of collaborationists under the command of Georgios Poulos.

On 2 July, 50 prisoners of war were executed at Vyrsodepseia in reprisal for Ersfeld's death and later in the day, resistance fighters skirmished with a German patrol at Platamonas.

On the night of 11 July, a bridge was blown up 25 km (16 mi) north-west of Lamia as a German column passed through and 25 wagons of ammunition were destroyed.

[21] In January 1944, the remnants of PAO, consisting of several hundred men, requested aid from the German authorities and they were reformed into collaborationist, counter-insurgency units.

The Treaty of Varkiza significantly weakened the communists, while the Greek army and gendarmerie were reformed with former members of anti-communist resistance organizations, including ex-collaborators.