How a brutal 16-year war finally drew the modern border between Iran and Turkey
Between 1623 and 1639, the Ottoman and Safavid empires clashed in a relentless struggle for control over Mesopotamia. Driven by religious dogma and imperial ambition, the two powers fought to a stalemate that ultimately reshaped the map of Western Asia, establishing a frontier that persists to this day.
The conflict began when Shah Abbas the Great, seeking to exploit internal Ottoman instability following the murder of Sultan Osman II, launched an offensive to reclaim Iraq. In January 1624, Safavid forces captured Baghdad, marking a significant blow to Ottoman prestige. The Shah attempted to transform the city into a purely Shiite stronghold, leading to the massacre of many Sunni inhabitants. This victory triggered a series of counter-offensives, as the Ottomans struggled to balance their eastern front with ongoing wars against the Habsburgs in Europe.
The war was characterized by harsh conditions and shifting fortunes. In 1625, Grand Vizier Hafız Ahmed Pasha besieged Baghdad but was forced to withdraw after supply lines were cut. By 1629, the Ottomans, having secured peace in the west, attempted to invade Persia proper under Gazi Hüsrev Pasha, though severe winter weather and flooding stalled their progress. The conflict devolved into years of raiding and skirmishes, with neither side able to secure a decisive advantage until Sultan Murad IV took personal command of the Ottoman army in 1635 and again in 1638.
The final turning point arrived in December 1638, when Murad IV recaptured Baghdad after a 39-day siege. This victory led to the Treaty of Zuhab on 17 May 1639. The treaty irrevocably ceded Mesopotamia to the Ottomans, while confirming Safavid control over regions like Dagestan and eastern Georgia. By re-establishing the borders roughly as they existed in the 1555 Treaty of Amasya, the agreement created a permanent equilibrium of power. This settlement effectively ended the century-long rivalry over the region, leaving a legacy that defines the modern western borders of Iran with Iraq and Turkey.
Source: Ottoman–Safavid War (1623–1639)
