Royal youngsters explored a woodland wilderness garden, caused mischief at a regatta and welcomed a new addition to the family this year.
Milestone birthdays and a school start shaped 2019 for the youngest generation of Windsors, with the birth of Archie Mountbatten-Windsor meaning an eighth great-grandchild for the Queen. For more on what the youngest members of the royal family got up to this year, read on.
Prince Louis
Louis turned one in April, with the Duke and Duchess of Cambridge releasing images of the toddler, showing his rosy cheeks and two bottom front teeth.
He made his first appearance on the Buckingham Palace balcony for the Trooping the Colour celebrations.
Clapping and waving at the crowds, at one point Louis sucked his thumb as William held him.
Princess Charlotte
Charlotte celebrated her fourth birthday.
William told children's writer Julia Donaldson at an investiture that he was preparing to stage a "rowdy" birthday party in May for his daughter with lots of youngsters invited.
Photos were released of Charlotte in a floral summer Betsy dress by Trotters as she sat cross-legged on a patch of grass at her Kensington Palace home.
Kate this year revealed that Charlotte was "pretty good" with spicy food, and also liked olives and, on a trip to Belfast, she referred to her daughter by the nickname "Lottie".
The fourth in line to the throne had fun poking her tongue out during the presentation ceremony at the King's Cup regatta on the Isle of Wight, after the duchess had encouraged her to wave.
Charlotte started school at private Thomas's Battersea in September.
She arrived for her first day with her parents and George, looking a little nervous at first as she fiddled with her pony tail.
William revealed his daughter was "very excited" and royal fans noticed a sparkling pink unicorn key ring affixed to her new school bag.
Archie Mountbatten-Windsor
The Duke and Duchess of Sussex's baby son Archie arrived just a few days after Charlotte's birthday.
He made his world debut wearing a white bonnet and wrapped in a shawl in the grand surrounds of Windsor Castle, with his proud parents.
Meghan described him as having the "sweetest temperament", adding: "He's really calm."
His place of birth was kept a secret until his birth certificate revealed he was born at the private Portland Hospital.
Like most royal christenings Archie's was private, but Harry and Meghan also decided not to release details of their son's godparents.
Archie later went on his first official royal tour when the Sussexes travelled to South Africa in September.
Aged four months, he received a welcome kiss from Archbishop Desmond Tutu in Cape Town.
The royal baby stole the show by giggling, smiling and captivating the anti-Apartheid movement hero.
Harry said about his son: "He's so busy, constantly wanting to stand."
Prince George
Prince George turned six on July 22, a moment that was celebrated with a series of portraits taken by his mother Kate Middleton. Photographed on holiday in an undisclosed location, Prince George was seen grinning with a mouth full of missing teeth in a grassy field.
In fact, 2019 was the year that it became clear Prince George had inherited his parents' love of sport. He captured hearts everywhere when he was taken to a Premier League match, where he was filmed cheering and jumping up and down as Aston Villa scored a goal against Norwich.
Given that Prince George's mother is Kate Middleton, the patron fo the All England Club, tennis was going to feature in the royal's life in some capacity. While sitting next to Kate Middleton, professional tennis player Anne Keothavang claimed that Prince George was "apparently quite a good player" while talking to Wimbledon Coffee Morning. It turns out that Prince George has had some pretty incredible tutors, as Koethoavang said, "George’s favourite tennis player is Roger Federer, and he’s actually got to play with him."
He also became an unexpected internet meme, after a parody account run by Family Guy writer Gary Janetti saw a spike in followers this year.
Counting celebrity fans including Sophie Turner, Sarah Michelle Gellar, Mandy Moore and Billie Porter amongst its following to name just a few, it imagines the royal at his sassiest.
Prince George also helped with the preparations for Christmas this year, as he was pictured helping make a Christmas pudding alongside Prince William, Prince Charles and Queen Elizabeth - making for a significant four generation festive portrait.
And of course, he also joined the rest of the family at Christmas mass where he was seen wearing a dapper suit.
Additional reporting by PA.
