Formerly part of the Aleppo Vilayet of the Ottoman Empire, the Sanjak of Alexandretta was occupied by France at the end of World War I and constituted part of the French Mandate of Syria.
The Sanjak of Alexandretta was an autonomous sanjak from 1921 to 1923, as a result of the French-Turkish treaty of October 20, 1921, considering the presence of an important Turkish community along with Arab and Armenian ones. Then it was attached to the State of Aleppo, then in 1925 it was directly attached to the State of Syria, still with a special administrative status.
Turkey under Mustafa Kemal Atatürk refused to accept the Sanjak of Alexandretta to be part of the Mandate and, in a speech on March 15, 1923 in Adana, claimed, that it was "a Turkish homeland for 40 centuries" and that "can't be a captive at the hands of enemy". In truth, the Turks first appeared in Anatolia during the 11th century when the Seljuk Turks occupied the eastern province of the Abbasid Empire and captured Baghdad. Turkish politics aimed at incorporating the Sanjak of Alexandretta when the French mandate of Syria would expire in 1935. Local Turks initiated reforms in the style of Atatürk's, formed various organisations and institutions in order to promote the idea of union with Turkey.
In 1936, the elections returned two Syrian independentist MPs (favoring the independence of Syria from France) in the sanjak, and this prompted communal riots and passionate articles in the Turkish and Syrian press. In particular, Arab nationalist Zaki al-Arsuzi was influential in anti-irredentist agitation.
In response, Atatürk government coined the name Hatay for the Sanjak of Alexandretta, as a reference to Hittites (Syro-Hittite states), and raised the "Issue of Hatay" (Turkish: Hatay Meselesi) at the League of Nations. On behalf of the League of Nations, representatives of France, the United Kingdom, the Netherlands, Belgium and Turkey prepared a constitution for the sanjak. The new statute came into power in November 1937, the Sanjak becoming 'distinct but not separated' from Syria on the diplomatic level, linked to both France and Turkey for defense matters.
Protests in Damascus in 1939 by women demonstrators against the secession of the Sanjak of Alexandretta, and its subsequent joining into Turkey as the Hatay Province. One of the signs reads: "Our blood is sacrificed for the Syrian Arab Sanjak."
In 29 June 1939, following a popular referendum, Hatay became a Turkish province. This referendum has been labelled both "phoney" and "rigged", and a way for the French to let Turks take over the area, hoping that they would turn on Hitler. For the referendum, Turkey crossed tens of thousands of Turks into Alexandretta to register as citizens and vote.
Syrian President Hashim al-Atassi resigned in protest at continued French intervention in Syrian affairs, maintaining that the French were obliged to refuse the annexation under the Franco-Syrian Treaty of Independence of 1936.
On June 29, 1939, the Hatay legislature voted on disestablishing the Hatay State and joining Turkey in order to increase the Turkish proportion of the population.. On July 7, 1939, the Grand National Assembly of Turkey approved the law establishing the Hatay Province and incorporating districts from Adana Province (then Seyhan Province) and Gaziantep Province. By July 23, 1939, the last vestiges of the French Mandate authorities had left Antakya, and the territory was fully annexed to Turkey. The result was a flight of many Arabs and Armenians to Syria. The region's Armenian population had particular reasons to be fearful, having been survivors of the Armenian Genocide and who had fled for their lives to the French Mandate of Syria and were now forced to leave again by the Turks.