Meet Susan, the Queen's first corgi. She went on her honeymoon in 1947 and most of the Queen's corgis descended from her.

• Queen Elizabeth's last two corgis appeared at her funeral committal ceremony in Windsor.
• The Queen loved corgis, and all but two of her dogs descended from her first, named Susan.

One of the most poignant moments at the funeral of Queen Elizabeth II was the glimpse of her corgis waiting for her casket to pass by.

It was as if they wanted to pay their final respects to their beloved owner.

The moving images of the dogs — together with photographs of Emma, the late monarch's last pony — struck a chord with mourners across the world. Corgis had been a signature of the Queen for more than seven decades.

She doted on the short-legged pets, including Muick and Sandy, the dogs that her footmen brought to see her committal ceremony at Windsor Castle on Monday.

Queen Elizabeth II was given her first and favorite corgi on her 18th birthday

Muick and Sandy were relative newcomers to the royal household. They were given to the Queen as puppies to keep her company during the COVID-19 pandemic, and they offered comfort when her husband, Prince Philip, died last at the age of 99.

But Sandy and Muick — the latter is named after one of the sovereign's favorite lochs on her Scottish estate, Balmoral — represented a break from tradition. Neither of them descended from the Queen's first dog, a Pembroke Welsh corgi known as Susan.

The young Elizabeth was so enamored by Susan, whom she received in 1944 as an 18th birthday present from her father, George VI, that she bred her. She wanted Susan's legacy to be preserved through her puppies.

Susan, who stayed at Elizabeth's side for 15 years before she died, played a such significant role in her life, the dog will be the subject of a forthcoming children's book, "The Corgi and the Queen," set to be published next month.

The author, Caroline Perry, told Insider that Susan's family tree showed that she had dozens of descendants. Perry said many of them were raised by the monarch. The Queen was believed to have owned at least 30 corgis during her unprecedented 70 years on the throne.

The Queen wanted Susan's legacy to be upheld

"Susan was the Queen's first love and their friendship sparked a dynasty across 14 generations," Perry said.

"She was clearly in love with this little animal and didn't want things to end," she added.

The monarch put a stop to the breeding program in 2018 following the death of a treasured corgi named Willow. Willow turned out to be the last of Susan's descendants. "The Queen said she didn't want them to outlive her," Perry said.

Perry, a former journalist, spent months researching Susan's story for her book. She discovered that the UK's head of state yearned for her precious corgi whenever they were apart.

She smuggled the pet inside her wedding carriage so Susan could join her on her honeymoon in Scotland, following her marriage to Prince Philip in 1947, Perry said.

"She hid her under a woven rug on the floor of the carriage when she rode across London to greet the hundreds of thousands of well-wishers," Perry said, adding, "It was probably a breach of royal protocol."

Perry said that none of the Queen's other dogs saw her through such "challenging times" as World War II and her coronation in 1953, "which happened under the sad circumstances of her father's death" the year before.

Perry said that Susan was 'feisty' and 'a little bit wild'

"A Queen can't really choose her own friends, but Susan was her chosen friend," she said.

Perry added, "She was very much a confidante and Elizabeth could show her true emotions to that little dog."

Perry described Susan as "feisty," which, she said, "was interesting because the Queen was very much not that way."

"The Queen was orderly and disciplined, and I think that's part of what she loved about Susan," Perry said. "She was sweet and affectionate, but she was a little bit wild. Maybe she was doing things that the younger Elizabeth wasn't allowed to do."

Susan once sank her teeth into a clock winder at one of the Queen's residences, according to Perry, and once bit a police officer.

"Luckily she didn't cause any damage," Perry said. "Corgis are playful and occasionally ankles do get nipped."

Susan was buried in a pet cemetery that was first established for royal pets by Queen Victoria

"In Elizabeth's sights, Susan was a staunch defender who could do nothing wrong," Perry said.

The Queen was heartbroken when Susan died in 1959. She was buried in a pet cemetery that Queen Victoria had founded on the Windsor estate of Sandringham. Perry said that Elizabeth chose the inscription on Susan's grave and visited the spot.

"She wrote a letter to one of her correspondents, saying that she'd always dreaded losing Susan," Perry said. The author concluded, "A lot of people might say, 'It was just a dog,' but the Queen never forgot her."