To understand what was happening in her life at that age, it's important to remember:
* She was a princess: Elizabeth was the daughter of King Henry VIII and Anne Boleyn. At that age, her life would have been focused on royal duties and her upbringing as a high-born lady.
* Her family was in turmoil: Henry VIII had been married three times before Anne Boleyn, and he was notorious for his political and personal upheavals. Elizabeth's childhood was far from stable.
While there isn't a "famous event" at age 3, her life was already heavily influenced by the events of the English court.