[6] In 1916, Grivas moved to Greece; according to his obituary in The Times of London, he had left the family home after learning that his father intended him to become a physician.

He served in the Hellenic Army's 10th Division and participated in its advance from Smyrna to Panormos (today Bandirma) and Eskişehir, past Bursa and the Battle of Sakarya.

[11] With the beginning of World War II, Grivas was transferred to the operations department of the central headquarters of the Hellenic Army, working on the strategic defensive plans for Northern Greece.

During the events of December 1944, members of Organisation X, using weapons recovered from the retreating Germans, fought at the Theseon alongside Greek and British monarchist forces to prevent EAM/ELAS fighters to take control of Athens.

Following his retirement, Grivas focused on the idea of ridding Cyprus of British colonial rule and eventually uniting it with Greece (Enosis).

[22] On 1 April 1955 with a declaration that he signed as DIGENIS and a number of bombings against various targets in the four major cities and military installations, he announced the beginning of his campaign for Self Determination – Union with Greece.

A month later, chased by the British forces, he was secretly transferred from the mountains by the car of a passionate EOKA fighter, Kostis Efstathiou, also known as "Pachykostis", and found refuge in a hideout at Limassol from where he directed not only the military activities but also the political campaign, since Archbishop Makarios in March 1956 was exiled by the authorities.

[32][33] From 1968 to 1969, under strict surveillance, Grivas participated in a resistance movement aiming at deposing the ruling military junta and restoring democracy in Greece, along with a number of Greek Army officers including Colonel Dimitrios Opropoulos and Majors Spyros Moustaklis, Nikolaos Lytras and George Karousos as well as Greek Cypriot students and professionals many of them former EOKA fighters.

[34][35][36][37] After the discovery of Grivas' plans by the authorities, he secretly returned to Cyprus on 31 August 1971, where he formed the armed organisation EOKA B, which he used as leverage in his attempts to persuade or force Makarios to change his policy and adopt the line of "Self Determination – Union" with Greece.

[38] EOKA B didn't overthrow Makarios but the armed struggle led to a vicious circle of violence and anti-violence that amounted to civil war among the Greek-Cypriot Community from 1971 to 1974.

[8] The post-Grivas EOKA B then signed a secret agreement with Brigadier Dimitrios Ioannidis, the "invisible dictator" of Greece, and was controlled directly from Athens.

[41] The coup d'état of 15 July 1974 that overthrew Makarios was executed by forces of the Cypriot National Guard under direct instructions from Greece.