The Ministry of Defence announced honorary Army and RAF promotions for the Princess in recognition of her "invaluable contribution and commitment to the military".
WATCH: Princess Anne turns 70! Watch her most memorable moments
Anne has been made a General in the British Army and Air Chief Marshal in the Royal Air Force, bringing her rank in each of the services in line with her existing role as Admiral and Chief Commandant of Women in the Royal Navy.
Until now her ranks within the Army and RAF were linked to her existing appointments as Colonel-in-Chief and Colonel of certain Regiments, and Honorary Air Commodore of RAF Brize Norton.
A palace spokeswoman said the move had been "approved by the Queen in line with longstanding convention covering military promotions for members of the royal family."
Princess Anne has been made a General in the British Army
The MoD said: "Her Royal Highness has been hugely supportive of the Armed Forces and undertaken a vast amount of work for the services over many years.
"This promotion on her 70th birthday recognises her invaluable contribution and commitment to the military. This includes long-term links with the Royal Navy, initially through the Women’s Royal Naval Service and her promotion to Admiral Chief Commandant in 2012.
"More recently, she visited the Royal Logistic Corps in Northern Ireland and paid tribute to the Royal Corps of Signals to mark their 100th birthday in June."
Princess Anne wears a dress by Maureen Baker. Credit: John Swannell / Camera Press
Ahead of her big day, the royal released three striking new official portraits.
Princess Anne, who is spending her birthday sailing along the West Coast of Scotland with her husband Vice Admiral Sir Tim Laurence, posed for John Swannell, the renowned photographer who has documented her milestone birthdays for the past four decades.
They were shot at Gatcombe Park - the private Gloucestershire home where she lives surrounded by her children, grandchildren and beloved horses.
Anne is seen in a flowing pale-yellow dress by Maureen Baker, the same designer who created her wedding dress in 1973 and who retired in the 1990s. The matching bolero is by a local designer Sue Palmer, who also created the emerald green outfit she wears in another of the new birthday portraits
A third shows her in off-duty country attire, posing in the woods on her estate, the first shoots of spring just visible in the background.
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