The settlement's history goes back to the 19th century, when the area was part of the Ottoman Empire. Long used as a landing ground for fishermen from the coast of Samothrace opposite, a hamlet developed in the area during the construction of a railway line connecting Constantinople to the major cities of Macedonia from Kuleliburgaz. The work was part of an effort to modernise the Empire, and was assigned to engineers from Austria-Hungary. The settlement soon grew into a fishing village known as Dedeağaç.In the late 19th and early 20th century, Dedeağaç was part of the Adrianople Vilayet of the Ottoman Empire.
Dedeağaç was captured by the Russians during the Russo-Turkish War of 1877–1878, and Russian forces settled in the village. The officers in charge saw that reconstruction incorporated wide streets running parallel to each other, allowing the quick advance of troops, and avoided cul-de-sacs. This was very unlike the narrow alleys, cobbled streets, and dead-ends that were characteristic of Ottoman cities at the time. The city returned to Ottoman control by the end of the war, but the brief Russian presence had a lasting effect on the design of Alexandroúpoli's streets.
The building of a railway station in Dedeağaç led to the development of the village into a town, and a minor trade centre by the end of the century. The town became the seat of a Pasha as the capital of a sanjak. Ottoman control of the town would last until the Balkan Wars. On 8 November 1912, Dedeağaç and its station was captured by Bulgarian forces with the assistance of the Hellenic Navy. Bulgaria and Greece were allies during the First Balkan War, but opponents in the Second Balkan War. Dedeağaç was captured by Greek forces on 11 July 1913. The Treaty of Bucharest (10 August 1913) however, determined that Dedeağaç would be returned to Bulgaria along with the rest of Western Thrace.
The defeat of Bulgaria by the Allies in World War I (1914–1918) ensured another change of hands for the town. Western Thrace was withdrawn from Bulgaria under the terms of the 1919 Treaty of Neuilly. Alexandroupoli was under temporary management of the Entente led by French General Charpy. In the second half of April 1920 in San Remo conference of the prime ministers of the main allies of the Entente powers (except USA) Western Thrace was given to Greece. However, Bulgaria retained the right of transit to use the port of Dedeagach to transport goods through the Aegean Sea. The change of guard between French and Greek officials occurred on May 14, 1920 in the city's Post Office. In the interior of the Post Office there is a memorial plaque concerning this event. The city was soon visited by Alexander of Greece. He was the first King of Greece to visit the town which was renamed in his honour.
Following the defeat of Greece in the Greco-Turkish War (1919–1922), the Greek Army under General Theodoros Pangalos retreated from Eastern Thrace to the area of Alexandroupoli. Bulgaria used the opportunity of the Greek defeat to demand that Alexandroupoli either be returned to its control or declared a neutral zone under international control. Both demands were soundly rejected by the Greek leadership and found no support in the League of Nations.The Treaty of Lausanne (24 July 1923) affirmed that Western Thrace and Alexandroupoli would continue to be controlled by Greece. A previous agreement allowing a Bulgarian presence in the town port had expired.
During World War II (see Axis occupation of Greece), the Nazis gave Alexandroupoli to their lesser Bulgarian partners Alexandroupoli was subsequently under Bulgarian occupation between May 1941 and 1944. The city suffered some damage to buildings and loss of population during the war, but was largely spared the effects of the Greek Civil War (1946–1949). Forces of the communist Democratic Army of Greece in and around the town area were small and loosely organized, resulting in the absence of major battles in the area; the return of peace allowed for Alexandroupoli to grow from a town of 16,332 residents in 1951 to a city of 57,812 residents by 2011.ModernIt has a sister city, Edirne, since November 30, 2007.
source: www.wikipedia.org