1378:

Western Schism Begins

The Avignon Papacy came to an end when Pope Gregory XI returned the papal see to Rome, then died before he could return to France. A Roman was elected to succeed him and took the name Urban VI. Urban was so hostile to the cardinals, who had achieved considerable power during the papacy's years in France, that thirteen members of the Sacred College went into conclave and chose another pope. This antipope took the name of Clement VII and took up residence at Avignon, beginning a schism that was characterized by the simultaneous administrations of two (and later three) popes, and which would last nearly 40 years.

1519:

Magellan Sets Sail

In his flagship Trinidad, Ferdinand Magellan led a fleet of ships in search of the Spice Islands. He would discover the strait that now bears his name, but he would die before one of the fleet succeeded in circumnavigating the globe.

The above events were suggested by Becky Kasper. Thanks, Becky!