Greeks 🇬🇷were robbed of their land in Northern Epirus 4 times during the 20th century.
1) The Greek Army crushed the occupying Ottoman army 🇹🇷 at the Battle of Bizani in March 1913 and liberated its land in Northern Epirus.
Austria-Hungary 🇦🇹🇭🇺 and Italy 🇮🇹 opposed larger Balkan states to be formed, particularly the Balkan League states to limit Balkan influence on the Adriatic and expanding Russian influence. At the Treaty of London 1913 and Protocol of Florence, the Great Powers forced Greece to give up Northern Epirus for Austria's newly made puppet albania 🇦🇱☪️.
2) Early 1914, Greeks of Northern Epirus 🇬🇷 resisted albo occupation and formed their own Autonomous Republic of Northern Epirus. Later in the year, the albos and their German Prince Wilhelm accepted autonomy for Greek Northern Epirus. However, this autonomy could not be fully implemented because of WW1 and the weak puppet state of albania already falling apart due to civil conflicts.
In October 1914, the Greek Army stepped in and entered Northern Epirus to regain its land. Local Northern Epirus Greeks welcomed the Greek Army as liberators. Esad Pasha, albo leader from Central albania, recognized Greek rule of Northern Epirus. Greece managed Northern Epirus up to September 1916, when Italy and France entered and occupied Northern Epirus for their own imperialist ambitions. They dismantled Greek institutions, gave the land for albos to manage, and promoted albo nationalism to counter Greeks.
3) In 1919, after the dissolution of Austria-Hungary and Greece's victory in WW1, Greece and Italy made a compromise at the Paris Peace Conference. This compromise awarded most of Northern Epirus to Greece, while Italy could retain its presence in Vlora.
Several year later during the Greco-Turk War, the Western Powers didn't put up a major effort to stop Ataturk's advancing forces. Italy took advantage of Greece's weakness and loss to reassign Northern Epirus to albos at the Conference of Ambassadors in 1921. albo King Zog would enact reforms to target Greeks such as an educational reform to close all Greek-language schools. Effectively, weakening and assimilating Northern Epirus Greeks as albos.
4) In 1939, Italy under Mussolini occupied all of albania including Northern Epirus with little to no resistance by albos. Italy then invaded Greece in 1940. The Greek Army repelled the invasion and counterattacked into Northern Epirus. Greece regained Northern Epirus and again were welcomed as liberators by the local Greeks just as they were in WW1. In April 1941, Nazi Germany 🇩🇪 invaded Greece and brought Northern Epirus back under fascist control again.
With the defeat of fascism in 1945, albo communists under the command of Enver Hoxha took control of Northern Epirus and declared it part of the "People's Republic of albania." Although Greece pressed the world powers at the Paris Peace Conference in 1946 to return Northern Epirus to them, the western powers along with Hoxha's backer, the USSR, refused any border revisions.
Hoxha would heavily repress Greeks in Northern Epirus through restrictions on language, religion, education, and freedom of movement. Hoxha's isolationist policy also closed the door for communication Northern Epirus Greeks and their motherland Greece.