The King has returned to the Royal Marines training base where he completed his helicopter pilot training 50 years ago.
Charles arrived at the Commando Training Centre Royal Marines in Lympstone, near Exeter, Devon, on Friday to meet successful recruits and present special honours.
He attended the training centre 50 years ago, completing three days commando training there as part of his pilot training in 1974.
He was presented with a picture of himself tackling the high ropes at the training centre, while he watched recruits perform the same manoeuvre.
The ropes are part of the Tarzan assault course, one of four gruelling commando tests Marines must complete to wear the green beret.
It was the first time a king has presented the badge since his grandfather, King George VI, in 1939.
It is given to the recruit deemed the most impressive of those passing through training.
He also met 100-year-old D-Day veteran Norman Ashford, a coxswain on a landing craft who did numerous runs up Gold Beach.
Mr Ashford is affectionately known by today’s Royal Marines as Grandad and returned to the Normandy beaches in June to pay homage to his comrades on the 80th anniversary.
Mr Ashford said: “It was a great honour to meet the King, I haven’t met royalty before and I just turned 100 on the 10th.
“It was a great pleasure to be back at the Commando Training Centre.”
Addressing the recruits, he said: “As your Captain General, I can only express my pride in each and every one of you, together with my admiration for passing such a demanding course.
“We are fortunate indeed to be able to rely on you, as well as on those families here today who so loyally support you.”
Marine Stephens, 20, was selected for the King’s Badge after completing his training despite previously picking up a serious injury.
After ten months recuperating, he resumed his training this autumn and completed his final five weeks to earn the badge.
“This moment will stay with me forever. I know the last time a King presented the King’s Badge was back in 1939, it’s quite daunting to think that I will be only the second Royal Marine to enjoy that honour,” he said.
“But with determination I took the knock, got back up again and got myself back to where I wanted to be.”
Marine Ryan triumphed after sustaining a lengthy shoulder injury late in training and spent five months recuperating and rehabilitating.
Marine Ryan, 20, received the Commando Medal for epitomising the commando spirit and ethos through his conversion from civilian to Royal Marine.
To acknowledge that achievement, he was singled out to receive his green beret, the Commandos’ headgear, from the King.
“Being presented my green beret by the King is amazing, honestly the biggest honour I could ever have.
“The lads in the troop have been brilliant, a really great bunch of guys, we’ve been through so much in the past few weeks together.”
As he left the base the King was presented with a picture of his visit on Friday, set side by side with one of George VI at the training centre in 1939.
The King jokingly said “that was very quick”.
Colonel Innes Catton said: “It’s the first time in 85 years the sovereign as our Captain General has come and presented the King’s Badge, which for us is a symbol of absolute excellence for our best recruit.
“As he got out of the car down here (by the assault course) there was a proper beaming smile.
“He was remembering (his time on the assault course), he wasn’t very kind in his description about it, he said it was quite uncomfortable but nonetheless enjoyed recalling it and asked the recruits about their experiences.”