Prince Philip, the Duke of Edinburgh, has died at the age of 99.

The Duke passed away this morning at Windsor Castle, the Royal Family announced in a statement.

"It is with deep sorrow that Her Majesty The Queen has announced the death of her beloved husband, His Royal Highness The Prince Philip, Duke of Edinburgh," the statement read. "His Royal Highness passed away peacefully this morning at Windsor Castle. The Royal Family join with people around the world in mourning his loss."

Prince William and Harry's grandfather has been at Queen Elizabeth's side since their marriage in 1947 and served as a constant companion throughout her more than six-decade reign. Prince Philip retired from official royal duties in August 2017 and enjoyed a quieter life after scaling back from public appearances.

The Duke didn't just marry into royalty, he was born into royalty. His father was Prince Andrew of Greece and Denmark, a son of King George I. His mother Princess Alice, was the eldest daughter of Louis Alexander Mountbatten and Princess Victoria of Hesse. She was also the granddaughter of Queen Victoria.

In 1947 Philip renounced his claim to the Greek and Danish throne and married his distant cousin, Queen Elizabeth that same year.

As a British royal, his life was not without plenty of controversies, including his sisters' marriage to high-ranking Nazi officials.

The Royal Family also stated that further announcements about Prince Philip's death will be made in "due course."

The royal is survived by his three children: Prince Charles, Princess Anne, Prince Andrew, and Prince Edward. He has eight grandchildren: Charles's sons, Prince William and Prince Harry; Anne's children, Zara Tindall and Peter Phillips; Andrew's daughters, Eugenie and Beatrice; and Edward's children, Louise and James.