What happened on a 21st of April

It is my birthday today. I learned from the Google Doodle that the 21st of April was also the birthday of Charlotte Brönte. I read her sister Emily, but not her. A strange anniversary for Google to celebrate: the 298th year of her birth. But it made me look for what happened on a 21st of April, the times in history when the date witnessed an important event. The first thing I noticed is of course the alleged Founding of Rome by Romulus. Being into Roman legends and history, this is something I am happy to have my date of birth associated to. And Romulus is also one of the legendary figures I particularly like, being called the "son of the she-wolf". I love wolves. So that's it, the 21st of April is the date when Rome was born, from the legendary labor and ambition of a man fed by a she-wolf. Kind of cool.