I've added some more topics. I don't know if they're the broadest and most important, though. In many cases, I'm sure they're not, but I don't know which ones would be so considered. Please, please check and edit the entries in your areas of expertise. See talk:Wikipedia arranged by topic.
... of Aragon, who was his aunt.
As Holy Roman Emperor, he called Martin Luther to the Diet of Worms in 1521, promising him safe conduct if he would appear. He ...