Hadrianopolis, the Byzantine fortress of Thrace where Valens died in 378 and Baldwin of Flanders was captured in 1205, taken by the Ottomans in the 1360s and their capital until 1453: the birthplace of Mehmed II and site of the Old Mosque and the Üç Şerefeli Mosque.
Edirne stands in eastern Thrace where the Tunca joins the Maritsa, on the old military road from Belgrade and Sofia to Constantinople. As Hadrianopolis, anglicised as Adrianople, it was the chief fortress of Byzantine Thrace, and the plain around it saw an emperor killed in 378 and another captured in 1205.
The Ottomans took it in the 1360s and made it the seat of the sultans for most of the next ninety years. From Edirne they directed the conquest of the Balkans; Mehmed II was born there in 1432 and prepared the siege of Constantinople there, and its mosques mark the stages by which Ottoman architecture moved from the style of Bursa toward the domed mosques of Istanbul.
The emperor Hadrian refounded a Thracian town here in the 120s and gave it his name. Constantine I defeated his rival Licinius outside it in 324, and on 9 August 378 the Goths destroyed the eastern Roman field army and killed the emperor Valens at the Battle of Adrianople, opening the Balkans to Gothic settlement.
In the Middle Ages the city guarded the approaches to Constantinople against the Bulgars. Khan Krum took it in 813 and deported its inhabitants beyond the Danube; later tradition placed the family of the future emperor Basil I among the captives. According to John Skylitzes, Tsar Samuel of Bulgaria plundered it in 1003, and in November 1189 Frederick Barbarossa, marching on the Third Crusade and at odds with the emperor Isaac II Angelos, occupied Adrianople and wintered his army in Thrace.
After the Fourth Crusade took Constantinople in 1204, Adrianople came under the Latin Empire, but in spring 1205 its Greek citizens rebelled and turned to the Bulgarian tsar Kaloyan. Baldwin of Flanders, crowned Latin emperor less than a year before, besieged the city with the Venetian doge Enrico Dandolo, and on 14 April Kaloyan's Cuman horsemen drew the Frankish knights out of their camp into an ambush. Baldwin was captured and died in captivity, and Geoffrey of Villehardouin, who led the retreat, left the fullest account.
For half a century the city passed between the Latins, the Greek magnate Theodore Branas, who held it as a fief from 1206, the rulers of Epirus and Nicaea and the Bulgarian tsar Ivan Asen II, before it returned to the restored Byzantine Empire. In the civil wars of the fourteenth century it was a political prize: the young Andronikos III raised his revolt there in 1321, its townspeople rose against the local aristocracy in 1341, and Matthew Kantakouzenos later ruled an appanage from the city, relying on Turkish allies.
The date of the Ottoman conquest is disputed. Ottoman chronicles place it in 1361 or 1362 and credit Murad I's commander Lala Şahin, but many historians put the fall later in the decade, probably about 1369. The metropolitan was carried off and died in captivity, and a synodal document of 1380 lamented that most of the townspeople, especially the leading families, had been taken away.
Murad made Edirne the base of the campaigns that made the Bulgarian tsars and much of Serbia subject to the Ottomans and ended with his death at the Battle of Kosovo in 1389. Bursa kept the dynasty's tombs, but the sultans increasingly lived in the Old Palace at Edirne, and Bayezid I ruled his Balkan conquests from it until Timur destroyed his army at Ankara in 1402.
After Ankara, Edirne became the capital of the European half of the divided state under Bayezid's son Süleyman, who began the Old Mosque in 1403. His brother Musa killed him in 1411 and ruled from Edirne until 1413, when their brother Mehmed defeated Musa and reunited the Ottoman lands. Mehmed I finished the Old Mosque, by most accounts in 1414, as a square hall of nine domes on four piers, and built beside it the bedesten, whose shop rents paid for the mosque. He died at Edirne in 1421.
His son Murad II had to fight for the city at once. Murad's uncle Mustafa, released by the Byzantines, was proclaimed sultan in the European provinces and entered Edirne, but Murad defeated him in 1422 and, by the Ottoman accounts, had him hanged, then besieged Constantinople the same year in retaliation.
Murad II made Edirne a court city. He built the Muradiye Mosque on a hill north-east of the town in about 1435, the long bridge over the Ergene at Uzunköprü between 1426 and 1443, and the Üç Şerefeli Mosque between 1438 and 1447, whose central dome, about 24 metres across, was far wider than any earlier Ottoman dome.
In June 1444 Murad made peace at Edirne with envoys from Hungary and then abdicated in favour of his twelve-year-old son Mehmed, born in the city on 30 March 1432. When a crusading army broke the peace, Murad returned and destroyed it at the Battle of Varna in November. In 1446 a Janissary revolt in Edirne brought him back to the throne, and he died there in February 1451.
Mehmed II spent the first two years of his second reign at Edirne preparing the attack on Constantinople; according to the Greek historian Doukas, the great bombard of the founder Orban was cast there early in 1453 and hauled toward the Bosphorus by teams of oxen. After the conquest the capital moved to Istanbul, but Mehmed enlarged the new palace on the Tunca meadows, and Edirne remained the sultans' second capital.