King Charles III is to become the next Captain General of the Royal Marines after Prince Harry was stripped of the title.
The Duke of Sussex lost the honorary military role after stepping down as a senior royal in 2021.
The king’s takeover comes after it was announced Prince Harry’s memoir will be released on January 10.
The duke was stripped of several titles, including Commodore-in-Chief of Ships and Diving, and Honorary Air Commandant of RAF Honington, after announcing last February that he would no longer be a working royal.
That meant he was not allowed to wear his military uniform during much of Queen Elizabeth II's funeral in September, despite having been on the front line during two tours of duty in Afghanistan. An exception was made when the queen’s grandchildren held a vigil by her coffin.
In a statement to mark the 358th anniversary of the Corps of Royal Marines, the king said he was "exceptionally proud" to become its ceremonial head.
"It is the greatest possible pleasure to assume the role of your Captain General," he said.
"I am exceptionally proud to follow in the footsteps of so many members of my family over the last three-and-a-half centuries, all of whom held the role with a deep sense of admiration.
"The Royal Marines have a distinguished and unparalleled history, both on land and at sea. I draw immense inspiration from your courage, determination, self-discipline and a remarkable capacity to endure in the most extreme environments.
"I feel greatly honoured to become part of the Corps Family and very much look forward to meeting many of you in the near future. In the meantime, this comes with my heartfelt and special wishes for a very happy 358th birthday."
He signed off “Per Mare Per Terram”, a Latin phrase and the Royal Marines’ motto, which means By Land and By Sea.
On Thursday, it was revealed the duke’s memoir, Spare, will go on sale on January 10, according to the publisher.
In September it was reported that Prince Harry was seeking last-minute refinements to his autobiography because he feared some of it may not be well received after Queen Elizabeth II’s death.
The Duke of Sussex was said to be worried that it may be seen as insensitive after the recent flood of support for the British monarchy.
Experts questioned whether the changes may have come too late for publisher Penguin Random House, which had by that point already signed off on the final draft.
It is not known whether changes were made to the book, which was ghostwritten by Pulitzer Prize-winner JR Moehringer and completed this summer.
The memoir will be available in English in the UK, Ireland, Australia, New Zealand, India, South Africa and Canada.
It will also be published in 15 additional languages, including Spanish, Italian, German and Chinese.
The memoir is part of a three-title deal worth £36.8 million ($39.9m).
Buckingham Palace declined to comment on the book's details.