"Day of wrath for Eastern Christendom, depicted on a Romanian fresco, came on May 29, 1453, when Constantinople fell after a seven-week siege by Mehmed II and 100,000 Ottoman troops. Manned by 8,000 defenders, the walls proved invincible to the largest cannon the world had yet seen—until a lightly guarded portal offered a way in."
From "The Byzantine Empire: Rome of the East," December 1983, National Geographic magazine