- Apr 7 Inquisitor-general Adrian Boeyens bans Lutheran books
Historic Event
Apr 7 Portuguese navigator Ferdinand Magellan's fleet reaches Cebu
Historic Event
Apr 16 Martin Luther arrives at the Diet of Worms assembly
- Apr 18 Diet of Worms: Cardinal Alexander questions Martin Luther
- Apr 21 Battle at Villalar: Emperor Charles I beats Communards
- Apr 22 French King Francois I declares war on Spain
- Apr 28 Treaty of Worms: Emperor Charles names his brother Ferdinand Archduke of Netherlands-Austria