The Ottoman Empire was founded by Osman I. As sultan Mehmed II conquered Constantinople (today named Istanbul) in 1453, the state grew into a mighty empire. The Empire reached its apex under Suleiman the Magnificent in the 16th century when it stretched from the Persian Gulf in the east to Hungary in the northwest; and from Egypt in the south to the Caucasus in the north. The empire came to an end in the aftermath of its defeat by the Allies in World War I. The empire was dismantled by the Allies after the war ended in 1918.