Orhan (c. 1323–1362), second Ottoman ruler, took Bursa, Nicaea, and Nicomedia from Byzantium, built the first Ottoman institutions — and planted the dynasty in Europe at Gallipoli in 1354.
Orhan inherited a hill-country ghazi band and left a two-continent state. Bursa fell as his father died (1326) and became the first real Ottoman capital; Nicaea followed in 1331 after the last Byzantine field army in Asia was beaten at Pelekanon, and Nicomedia in 1337 — the conquest of Byzantine Bithynia complete.
Byzantium's civil wars then opened Europe themselves: hired by John VI Kantakouzenos — who gave him his daughter Theodora in marriage — Orhan's troops learned the Thracian roads as allies, and in 1354, when an earthquake threw down Gallipoli's walls, his son Suleyman occupied the town. The Ottomans never left Europe again.
Orhan was born about 1281 in the Söğüt marches, where his father Osman was one frontier bey among a dozen heirs of the Seljuk collapse. He commanded in Osman's later campaigns as the emirate's little war of posts closed around Bursa.
The dynastic tradition records the succession as a model: Orhan's brother Alaeddin declining the throne or accepting the vizierate, the brothers dividing labour rather than the state — a story burnished later, but reflecting the fact that the Ottomans, almost alone among the beyliks, did not fragment at each succession.
The Byzantine statesmen who dealt with Orhan — Kantakouzenos above all, his father-in-law and ally-victim — describe a ruler of formidable practical intelligence: patient in siege, opportunist in alliance, scrupulous within a bargain and entirely unsentimental beyond it. The traveller Ibn Battuta, who saw him in the 1330s, called him the greatest of the Turkmen kings in wealth, lands, and forces, and noted his habit of ceaseless movement among his nearly hundred fortresses.
The institution-building shows the ambition behind the raider's manner: the first Ottoman silver coinage struck in his name, the first medreses and mosques at Iznik and Bursa, the yaya standing infantry that prefigured the Janissaries — a chieftain deliberately assembling the apparatus of a state, and marrying into the imperial house he was dismembering.
The Bithynian conquest was methodical: blockade rather than assault, the countryside strangled until Bursa (1326), Nicaea (1331), and Nicomedia (1337) opened their gates — the young Andronikos III and John Kantakouzenos beaten at Pelekanon in 1329 in Byzantium's last attempt to relieve Asia. The beylik of Karesi, absorbed in the 1340s, brought the dynasty to the Dardanelles shore.
Then Byzantium hired its own successor. In the civil war of the 1340s Kantakouzenos bought Orhan's six thousand horsemen with money, plunder-rights, and his daughter; Ottoman troops campaigned across Thrace as imperial allies for a decade, and when the earthquake of 2 March 1354 levelled Gallipoli's defences, Suleyman Pasha's men walked in and fortified it as a permanent bridgehead. Kantakouzenos's protests met the reply of a man who understood facts: God had opened the gate. Adrianople's fall — the next reign's work — was already implicit.
Orhan's eighty years spanned the whole transformation: born a chieftain's son among tents, he died a sovereign with a chancery, a coinage, two capitals, and a European province. The machinery his reign began — regular revenue, standing troops, the incorporation of Christian tributaries and renegades — is what separated the Ottomans from every rival beylik with equal courage and worse institutions.
Gallipoli proved the hinge of centuries: from that earthquake bridgehead came Adrianople, Kosovo, and ultimately 1453 — his great-great-grandson Mehmed II closing the circle around the city whose civil wars had shown Orhan the way across.