With the help of remarkable Thessalian horsemanship, Philip II achieved a spectacular victory over a Phoecian tribe. To celebrate, he named his daughter Thessalonike (literally, 'victory of Thessalians'). Later, when Thessalonike married the Macedonian general Kassandros, her name was chosen for the city of Thessaloniki, founded in 315 BC.
In 168 BC the Romans conquered Macedon. Thessaloniki's importance was enhanced by its ideal location on the Thermaic Gulf, the east–west Via Egnatia and the Axios/Vardar River valley leading north. Under Galerius, Thessaloniki became the eastern imperial capital; with the empire’s division in AD 395, it became Byzantium’s second city, a flourishing Constantinople in miniature.
However, it was also frequently attacked by Goths, Slavs, Saracens and Crusaders. Still, Thessaloniki remained a cultural centre. It bore the 9th-century monks Cyril and Methodius (creators of Glagolitic, precursor to Cyrillic), who expanded Orthodox Byzantine literary culture among the Slavs. The city also nurtured great 14th-century theologian St Gregory Palamas, who became Archbishop of Thessaloniki.
In 1430 the Ottoman Turks captured Thessaloniki; after 1492 they resettled Sephardic Jews fleeing the Inquisition to here, adding to the city's diversity.
With the 1821–27 War of Independence only a partial success, 19th-century Thessaloniki became a lurid hub for intrigue, secret societies and mutually antagonistic rebels and reformers. Along with Greek revolutionaries, these included the pro-Bulgarian Internal Macedonian Revolutionary Organisation (IMRO), and the Young Turks, who wanted Western-style reforms for the empire. Indeed, one Young Turk and Thessaloniki native, Mustafa Kemal (Atatürk), would become modern Turkey's founding father.
Thessaloniki suffered successive tragedies over the following four decades. The August 1917 fire burned two-thirds of it, and ethnic diversity shrank with the 1923 population exchanges. During the WWII Nazi occupation, Thessaloniki’s Jews were deported to concentration camps and other non-Greeks were expelled following the Greek Civil War.
Recent decades have brought cultural acclaim, including the city's 1997 reign as European Capital of Culture and its hosting of sporting events during the 2004 Athens Olympics. In 2014 Thessaloniki was European Youth Capital, thanks to having one of the largest student populations in Southern Europe.