Cilicia comprises the south coastal region of Asia Minor, as seen on the map. From December 1918 to October 1921, after the defeat of the Ottoman Empire in World War I, the French controlled Cilicia. Although Cilician Armenians sought to create an independent Cilician state under French authority, the French relinquished Cilicia to Turkey on October 21, 1921, under the Treaty of Ankara.
During this 23-month period, the French administration in Cilicia used stamps of Turkey, France, and the French Offices in Turkey overprinted T.E.O. Cilicie [Territoires Ennemis Occupés] or O.M.F. Cilicie [Occupation Militaire Francaise].
Surely mail between this short-lived political entity and Luxembourg must be uncommon as little connects the two countries. An example—the only one I’ve encountered—is the view card shown here, which was posted from Adana, Cilicia, on January 25, 1920, as part of a postcard exchange with a correspondent in Esch-sur-Alzette.
Two Cilicia overprints are tied to the view side by the Adana cancel: a 1916 Turkish 20-para commemorative showing the old general post office in Constantinople overprinted in black T.E.O. Cilicie and a 1-piaster Turkish pictorial from the 1913 issue showing the Mosque of Selim at Adrianople also overprinted T.E.O. Cilicie, but in red. On the reverse is the French Control Postal censor mark.
Quite a nice item if you enjoy unusual incoming mail to Luxembourg!