The Ottoman sultan, Bayezid II, in his message congratulated the first Safavid king (Shah) Isma’il on his victories and advised him to stop destroying the graves and mosques of Sunni Muslims. Shah Isma’il was convinced of the righteousness of his cause and the evil of Sunni Islam; he did ignore the request and later even massacred entire Persian towns that refused to accept Twelver Rafidi Shi’sim. The new sultan in Constantinople after 1512, Sultan Selim, warred against the extreme form of Twelver Rafidi Shi’ism that was enforced on the lands of Persia, he started killing 40,000 Shi‘is accused of being Kizilbash or Safavid agents, and imprisoned or deported thousands of others.
Sultan Selim waged war also against the Safavids. On 23 August 1514, just west of Tabriz in Chalderan plain, Shah Isma’il’s army suffered a crushing defeat, which its cavalry and infantry were armed with spears, bows and swords, fighting against Ottoman’s superior numbers as well as field artillery and musketeers. Shah Isma’il and his followers firmly believed that Allah was on their side, but they were confused by their military setback, Tabriz, their capital was briefly occupied. This battle and defeat of Safavid Shah paved the path for the Ottoman conquest of Diyarbakr, Erzinjan, and other parts of eastern Anatolia as well as northern Iraq. Shah Isma’il himself found relief from psychological depression in wine, and died ten years later, at the age of thirty-seven.
Reference: ‘The history of Shah Isma’il Safawi – The bringer of Shi’ism’ by the Iranian historian Amir Hussein Khonji