The relationship between the Ottomans and the Mamluks had been adversarial since the Fall of Constantinople to the Ottomans in 1453; both states vied for control of the spice trade, and the Ottomans aspired to eventually taking control of the Holy Cities of Islam. An earlier conflict, which lasted from 1485 to 1491, had led to a stalemate. By 1516, the Ottomans were free from other concerns—Sultan Selim I had just vanquished the Safavid Persians at the Battle of Chaldiran in 1514—and turned their full might against the Mamluks, who ruled in Syria and Egypt, to complete the Ottoman conquest of the Middle East.
Question: What happened second: the Fall of Constantinople or the Battle of Chaldiran?
Answer: the Battle of Chaldiran