This time five years ago, Prince George and Princess Charlotte were getting used to life with a new baby brother, after their mum Princess Kate gave birth to Prince Louis.
The young royal's fifth birthday celebrations last week was no doubt a momentous day for the family, but the date of his birth will go down in history for another reason too.
A change in the law in 2013 meant that when Kate gave birth to her Louis at 11.01am on April 23, 2018, Charlotte made history.
The little princess became the first female royal to retain her claim to the throne and not be bumped down the line by the arrival of a new male heir.
Before the Succession to the Crown Act 2013 came into force Princess Charlotte, who is currently third in line to the throne, would have been bumped down to fourth as Louis would have taken her old spot.
Instead, Louis is fourth in the line of succession after his grandfather dad Prince William and siblings George and Charlotte.
The last woman to be affected by this is Princess Anne.
When she was born in August 1950 she was second in line to the throne after her big brother Charles.
However, before long the Queen and Prince Philip had welcomed Prince Andrew and Prince Edward.
The boys overtook Ann, leaving her in fourth in line to the throne.
When she fell pregnant, she knew her children would be bumped even further down the list when their cousins were born, so opted against giving Zara and Peter HRH titles.
This allowed them to lead more normal lives and have careers of their own.
The world celebrated with Kate and William when they announced their little boy had been born.
The proud parents were greeted by excited royal fans and countless cameras as they walked out of the private maternity unit the Lindo Wing with their bundle of joy.
A statement from Kensington Palace said Kate had "safely" delivered royal baby number three this morning, just hours after being admitted to hospital and as the country marked patriotic St George's Day.
Little Louis weighed 8lbs, 7oz, and got to meet his brother and sister at the hospital before heading home to Kensington Palace.
