On 6 July 1974, Makarios accused the Greek government of turning the Cypriot National Guard into an army of occupation. On 15 July 1974, the Greek military junta and the Cypriot National Guard backed a Greek Cypriot military coup d'état in Cyprus. Pro-Enosis Nikos Sampson replaced President Makarios as the new president. The Greek Cypriot coupists proclaimed the establishment of the "Hellenic Republic of Cyprus". Turkey claimed that under the 1960 Treaty of Guarantee, the coup was sufficient reason for military action to protect the Turkish Cypriot populace, and thus Turkey invaded Cyprus on 20 July. Turkish forces proceeded to take over the northern four-elevenths of the island (about 36% of Cyprus's total area). The coup caused a civil war filled with ethnic violence, after which it collapsed and Makarios returned to power.