Lady Louise Windsor looks set to be the first female royal to serve in the military since her late grandmother, Queen Elizabeth II.
It was revealed last year that the Duke and Duchess of Edinburgh's daughter had joined the St Andrews' University Officers' Training Corps (UOTC).
In pictures published by The Sun, the 21-year-old is seen on a military exercise, wearing combat fatigues, camouflage paint on her face and holding a helmet that appears to be emblazoned with her surname 'Windsor'.
According to the newspaper, Lady Louise has had basic weapons training, leadership lessons and a course in navigating tough terrain under pressure.
The young royal is said to have fit the training in around her studies for her English degree.
Last summer, it was also reported that Lady Louise, who is 16th in line to the throne, had stated on her LinkedIn page: "I am interested in pursuing a career in the military, diplomacy, or law."
Prince Edward and Sophie's children – who also include 17-year-old James, Earl of Wessex – are not expected to carry out full-time royal duties once they have completed their education.
Lady Louise is in the third year of her English degree at St Andrews University in Scotland, having enrolled in 2022.
While many students graduate after their third year at university, unless they have opted to study abroad for a year, in Scotland, a four-year course is standard.
If Lady Louise enlists in the Army after her studies, she will be the first female royal to do so since 1945 when then Princess Elizabeth joined the Auxiliary Territorial Service (ATS).
During her time in the ATS, she learnt to drive and to maintain vehicles.
The King, then the Prince of Wales, has served in the Royal Navy, like his late father, Prince Philip, and trained in the Royal Air Force.
Meanwhile, Prince William previously was an RAF search and rescue pilot at RAF Valley in Anglesey Wales, while Prince Harry was part of the armed forces for a decade, undertaking two tours of Afghanistan.