Nowadays Erdogan frequently invokes and glorifies Turkey’s Ottoman past, reinforcing the impression that many hold, that he is intent on restoring the caliphate in Istanbul and maybe even declare himself caliph.

In any case, when he enters the Hagia Sophia and dedicates his Islamic prayer to “Istanbul’s conqueror,” he is inviting people to remember the Ottoman Sultan Mehmet II, the conqueror of Constantinople. In my forthcoming book The History of Jihad From Muhammad to ISIS (which you can preorder here), I recount how, after over seven hundred years of trying, the warriors of jihad finally entered the great city on May 29, 1453. When they did, they made the streets run with rivers of blood. Muslims raided monasteries and convents, emptying them of their inhabitants, and plundered private houses. They entered the Hagia Sophia, which for nearly a thousand years had been the grandest church in Christendom. The Muslims then killed the elderly and weak and led the rest off into slavery.

The Byzantine scholar Bessarion wrote to the Doge of Venice in July 1453, saying that Constantinople had been

…sacked by the most inhuman barbarians and the most savage enemies of the Christian faith, by the fiercest of wild beasts. The public treasure has been consumed, private wealth has been destroyed, the temples have been stripped of gold, silver, jewels, the relics of the saints, and other most precious ornaments. Men have been butchered like cattle, women abducted, virgins ravished, and children snatched from the arms of their parents.

When the slaughter and pillage was finished, Mehmet II ordered an Islamic scholar to mount the high pulpit of the Hagia Sophia and declare that there was no God but Allah, and Muhammad was his prophet. The magnificent old church was turned into a mosque; hundreds of other churches in Constantinople and elsewhere suffered the same fate. Millions of Christians joined the ranks of the dhimmis; others were enslaved, and many were killed.

These are the glories Erdogan was invoking.

“Turkish president recites Muslim prayer at the Hagia Sophia,” Associated Press, March 31, 2018 (thanks to The Religion of Peace):