I'll freely admit that this date meant nothing to me so I looked it up and here's the scoop for all the rest who didn't know either !
Extremely important date. The Fall of Constantinople just preceded Columbus' discovery of the New World in 1492. So, the Christian East fell at the same time that what would become the Christian Americas were opened to European settlement. And the Reformation that began in 1517 beget our modern Western civilization. The Muslim faith never underwent a reformation and many Muslims now seek to destroy Western civilization, which, unfortunately, is in such a state of decline at present relatively few wish to fight for its survival.