Sakarya

i.The Sakarya River and the Adapazarı Plain

Sakarya province sits on the broad alluvial plain at the western end of the Sakarya river — the ancient Sangarius, the third-longest river of Türkiye after the Kızılırmak and the Euphrates — at the point where the river leaves the inland Anatolian plateau and enters the eastern Marmara basin. The plain itself, the Adapazarı Ovası, is one of the most fertile in northern Türkiye: deep alluvial soil, abundant groundwater, the long warm summers of the Marmara climate. The country to its south rises in the foothills of the Samanlı Dağları, separating the province from the Gulf of İzmit; to the east, in low country, the river runs north toward the Black Sea coast at Karasu.

The provincial capital, Adapazarı, sits in the centre of the plain on the small island of higher ground that gave the town its modern name — Ada Karyesi, "Island Village" — from which Adapazarı derives. The defining geological feature of the province is the North Anatolian Fault Zone, which runs east-west across the country immediately south of the city. Its rupture of 17 August 1999 — treated in the present-note above — is the defining event of the modern provincial history.

ii.From Bithynia to Byzantine Sakarya

The country was, in antiquity, part of the kingdom of Bithynia — the Hellenistic-Roman kingdom centred on the gulf of İzmit (see our Kocaeli essay for the Bithynian framework) — and the Sangarius valley was its principal eastern frontier with Galatia and Phrygia. The river is mentioned in Homer (Iliad III.187) and in Greek geographical sources from the 6th century BCE onward. Through the Roman and Byzantine centuries the country was a working agricultural and military frontier zone, with garrison towns at Caenophrurium and Tatauion along the imperial road that ran from Nicomedia eastward.

The medieval Byzantine country was a frontier of the contracting empire after the Seljuk advance into central Anatolia following Manzikert (1071). Through the 12th and 13th centuries the Sangarius valley was the principal Byzantine military frontier with the various Turkmen frontier emirates that would, in the early 14th century, consolidate into the early Ottoman state.

iii.Orhan Gazi's Conquest of 1324

The Ottoman capture of the Adapazarı plain came as part of Orhan Gazi's consolidation of the southeastern Marmara following the conquest of Bursa in 1326. The principal local settlement on the plain — known to the Byzantines as Akmaa or Ada-Kasabası — fell to Ottoman forces in 1324, two years before Bursa, and was renamed Ada Karyesi in Ottoman registers, after the small island of higher ground in the surrounding marshes. The town remained a modest local market and administrative centre through the long Ottoman centuries, attached as a small kaza to the larger Kocaeli Sancağı.

iv.Late Ottoman Adapazarı — Migration and Trade

The transformation of Adapazarı into a substantial provincial town came in the late 19th century, after the 1877–78 Russo-Turkish War ("the 93 Harbi" in Turkish historical memory, for AH 1293). The war's catastrophic outcome — the loss of much of the Ottoman Balkans and the Caucasus to Russian advance — produced a major refugee movement of Muslim populations from the Balkans (Bulgaria, Bosnia, Rumelia) and the Caucasus (Circassia, Abkhazia, Chechnya) into the surviving Ottoman territories. The Ottoman government settled large numbers of these refugees on the underused Adapazarı plain, where the rich agricultural land could absorb them. The municipality of Adapazarı Belediyesi was established in 1868; through the late 19th century the town grew rapidly, with its population doubling several times. Adapazarı remains today a city whose demographic and cultural texture reflects, more than almost any other Anatolian centre, this late-Ottoman migration heritage.

The opening of the Haydarpaşa–İzmit–Adapazarı railway in 1899 linked the town to the eastern Marmara industrial corridor and accelerated its growth into a substantial agricultural-and-light-industrial centre by the early 20th century.

v.The 1920–21 Occupation and the Liberation of 21 June 1921

The Greco-Turkish War of 1919–22 reached the Adapazarı plain in 1920. The town was occupied by Greek forces three times during the war — including, in the Valilik's account, by collaborating local militias. The decisive Turkish recovery of Adapazarı came on 21 June 1921, when forces under the Turkish irregular commander Çerkez Ethem (later disowned by the national movement) and local Müdâfaa-i Hukuk militias under Halit Molla drove the Greek garrison and its supporters out of the town. The date is observed annually as Adapazarı'nın Kurtuluşu, the Liberation of Adapazarı.

vi.The Battle of the Sakarya — 24 August to 16 September 1921

The most consequential event of Sakarya's modern history is the great battle that gave the province its name: the Sakarya Meydan Muharebesi — the Battle of the Sakarya — fought between 24 August and 16 September 1921 along the line of the Sakarya river south of the modern provincial centre. Following the success of the Greek summer offensive of July 1921, which had carried the Greek army across western Anatolia to the line of the Sakarya only seventy kilometres west of Ankara, the Turkish Grand National Assembly conferred on Mustafa Kemal Paşa the title of Commander-in-Chief (Başkomutan) and the powers to organise the defence personally.

The battle that followed was the longest pitched engagement of the National Struggle — twenty-three days of continuous fighting along a hundred-kilometre front. Mustafa Kemal's order to his forces — "Hatt-ı müdafaa yoktur, sath-ı müdafaa vardır. O satıh bütün vatandır" ("There is no line of defence; there is a surface of defence. That surface is the entire homeland") — became one of the most-quoted lines in modern Turkish history. The Greek attack reached the heights of Mangaltepe and Çal Dağı, but never broke the Turkish line. On 16 September 1921 the Greek army began the retreat that would, a year later, end at İzmir. The Grand National Assembly conferred on Mustafa Kemal the title of Gazi ("warrior, victor") and the rank of Mareşal (Marshal) for the victory. The standard scholarly account is in Andrew Mango's Atatürk: The Biography of the Founder of Modern Turkey (Overlook, 1999); the standard military synthesis in Erik Zürcher's Turkey: A Modern History (4th ed., I.B. Tauris, 2017).

vii.The Republic and the 1954 Province

Through the early Republican decades Adapazarı remained an administrative subdivision of the Kocaeli province. The Grand National Assembly carved a new Sakarya province out of the eastern part of Kocaeli by Law no. 6418 of 17 June 1954, with the new province named for the river that ran through it and Adapazarı as its capital. The province's boundaries have not changed substantially since.

Under the Republic the city's economy diversified beyond the older agricultural base. The opening of the Otosan (later Ford Otosan) plant in the late 1950s, the Toyota plant at Arifiye in 1994, and a substantial network of automotive-supplier and machine-industry firms made the province one of the leading manufacturing centres of the eastern Marmara — second only to Kocaeli in the region. The opening of the Marmara Üniversitesi Adapazarı campus in 1992 (now the independent Sakarya Üniversitesi) anchored the city's modern academic life.

viii.The Modern Province

Under the TÜİK 2024 address-based registration count the province population was 1,110,735. The metropolitan municipality covers sixteen districts. The two central urban districts — Adapazarı (~282,000, the historic centre) and Serdivan (~166,000, the post-1999 western suburb that has absorbed much of the rebuilt city) — together carry about 40 per cent of the provincial population. The largest of the surrounding districts is Akyazı (~98,000), Hendek (~93,000) on the road east toward Bolu, Karasu on the Black Sea coast, and Sapanca, the small lakeside resort town twenty kilometres west of the provincial capital. The provincial economy continues to balance the older agricultural base (hazelnut from the Karasu coast, dairy, vegetables) with the manufacturing investment of the eastern Marmara industrial corridor.

ix.What to See, in Order

The walking shape of historic Adapazarı is small. From the central Atatürk Meydanı the route runs to the small Adapazarı Müzesi (with the regional archaeological and ethnographic collection), the post-1999 Mehmet Akif Camii (rebuilt over the foundations of the 1925 Çark Camii), and the modern Atatürk Bulvarı with its restored late-19th-century timber-framed houses. The principal monumental complex in the province is at the small lake town of Sapanca, west of Adapazarı, with its waterfront promenade and the surrounding forested hills.

For the wider province, the principal excursions reach the Sakarya battlefield monuments south of the modern city — the various small commemorative parks and the Mangaltepe and Çal Dağı positions of the 1921 battle, often visited as a half-day route from Polatlı (in Ankara province but accessible from Sakarya) and the small Polatlı Atatürk ve Sakarya Meydan Muharebesi Müzesi. North, the small Black Sea coast at Karasu offers the long beach that the river opens onto at the sea.

The Marmara plain of the Sangarius — Ottoman Ada Karyesi, the migration-built late-Ottoman town, and the battlefield where Mustafa Kemal Paşa earned the title of Gazi.

For the parallel Marmara industrial province to the west and the same 1999 earthquake, see Kocaeli; for the wider Marmara basin, see İstanbul and Bursa. For Türkiye's Marmara coast and its faults in the wider sense, visit our sister site CountryOfTurkey.com.