The Battle of Tillyria (Greek: Μάχη της Τηλλυρίας) or Battle of Kokkina (Greek: Μάχη των Κοκκίνων), also known as Erenköy Resistance (Turkish: Erenköy Direnişi), was a conflict on 6 August 1964 between units of the Cypriot National Guard and Turkish Cypriot armed groups in Kokkina area of Cyprus.

In 1964, at the time of the battle, Cyprus was governed by two sovereign state entities—the Republic of Cyprus and the British Sovereign Base Areas. The areas under the jurisdiction of the Republic of Cyprus included a number of large and fortified enclaves, inhabited by the island's Turkish Cypriot minority, which had receded into defensive positions around Turkish controlled villages following a major outbreak of civil unrest in 1963.

The Tillyria region of Cyprus was largely enclosed within the Morphou Administrative District in the north-west of the island, forming a large portion of the southern coastline of Morphou Bay. Located on this coastline at Kokkina was a heavily fortified Turkish enclave with between 750 and 1000 inhabitants.

In November 1963, the President of the Republic of Cyprus, Archbishop Makarios III, proposed 13 constitutional amendments to the Constitution of the country's Government. These amendments were primarily aimed by the Makarios Administration at reorganising and regulating the distribution of Greek Cypriot and Turkish Cypriot manpower and voting power in the Government, civil services, military and police forces. These proposed amendments would also have affected the distribution of Greek Cypriot and Turkish Cypriot persons serving the judicial, executive and municipal service arms of the Government, in favour of a 70% to 30% split, weighted to the Greek Cypriot population majority (77%) over the Turkish Cypriot minority (18%).

While the Greek Cypriot and Turkish Cypriot sides of the Government were already largely polarised in favour of the interests of their respective "mother-states" (Greece and Turkey), the Turkish Cypriot representatives within the Government rejected Makarios' 13 proposed constitutional amendments, on the basis that it deprived the Turkish Cypriots of equal representation.

This resulted in the escalation of the Cypriot intercommunal violence in the events named the "Bloody Christmas", and the end of the Turkish Cypriot representation in the government of the Republic of Cyprus.

A series of atrocities and intercommunal terrorist acts struck the island from 20-21 December 1963, as violence began to flare between Turkish and Greek Cypriot extremists. This violence escalated quickly and was reinforced by pre-existing nationalist sentiments on both sides, including a Turkish desire for "Taksim" (or division of the island into Turkish and Greek portions), and a Greek desire for "Enosis" (or union of the entire island with Greece). The main proponents of this violence were the Turkish Resistance Organisation (TMT), and the Greek Cypriot paramilitaries though it is not clear how much of the violence can actually be attributed to directives issued by these groups.

In mid-1964 the Cypriot Government became aware that the Turkish Cypriots, who by now had almost universally receded into enclaves nationwide, were becoming increasingly well equipped with small arms, squad automatic weapons and mortars that would not have otherwise been made available to them through legal ports of entry. The Turkish Cypriot-held deep-water dock at Kokkina, in Tillyria region, was immediately suspected as the focus of a Turkish shipping point for the supply of arms to the Turkish Cypriots from mainland Turkey.