The two-year-old made history when her brother entered the world, thanks to the Succession to the Crown Act of 2013.
Why did Princess Charlotte make history?
Princess Charlotte became the first female royal to retain her claim to the throne, despite the royal baby being a boy.
Before the Succession to the Crown Act 2013 a son would leap over an older daughter in the line of succession.
Therefore Princess Anne, despite being the Queen's second child, was in the line of succession beneath her younger brothers Andrew and Edward.
Princess Charlotte is the first royal not ruled out by gender.