Al-Mahdi vs Selim I

Al-Mahdi oversaw the completion of the Round City of Baghdad, the new Abbasid capital founded by his father al-Mansur. This city became a center of trade, learning, and culture, symbolizing Abbasid power.

Al-Mahdi led military campaigns against the Byzantine Empire, including a major expedition in 775 that reached as far as the outskirts of Constantinople. These campaigns were part of the ongoing Arab-Byzantine wars and resulted in territorial gains for the Abbasids.

Al-Mahdi dispatched forces to suppress a Kharijite rebellion in the Jazira region. The revolt was crushed, and its leaders were executed, reinforcing Abbasid control over the region.

Al-Mahdi supported the translation of Greek, Persian, and Indian scientific and philosophical texts into Arabic. This patronage contributed to the Abbasid Golden Age and the preservation of classical knowledge.

To secure his succession, Selim I ordered the execution of his brothers, Prince Mustafa and Prince Korkut, who were potential rivals for the throne. This act followed the Ottoman practice of fratricide to prevent civil war. It eliminated internal opposition and consolidated Selim's rule.

Selim I led the Ottoman army against the Safavid Empire under Shah Ismail I at Chaldiran in eastern Anatolia. The Ottomans, using superior artillery and gunpowder tactics, decisively defeated the Safavids. This victory secured Ottoman control over eastern Anatolia and prevented Safavid expansion westward.

Selim I led a campaign against the Mamluk Sultanate, defeating them at the Battle of Marj Dabiq and the Battle of Ridaniya. He conquered Cairo and the Hejaz, including the holy cities of Mecca and Medina. This brought the Islamic caliphate under Ottoman control and expanded Ottoman territory into North Africa and Arabia.

After conquering Cairo, Selim I received the keys to the Kaaba and the relics of the Prophet Muhammad from the last Abbasid caliph, Al-Mutawakkil III. Selim I assumed the title of Caliph, claiming spiritual leadership of the Islamic world. This transfer established the Ottoman sultans as caliphs until 1924.