The Duke of Sussex scrambled through mud, climbed up a rope and threw a spear in a military-style assault course with James Corden that showed off his strength.
Prince Harry, who spent ten years in the Army and went on two tours of Afghanistan, also climbed over a frame and ran with a heavy ball in the exercise in Los Angeles.
Corden organised the course as 'a little something to take you back to your roots' during a segment on The Late Late Show during which he interviewed the royal.
The challenge had eight obstacles which the organiser named Sam told Harry, 36, and Corden, 42, were designed to test them 'mentally, physically and spiritually'.
Prince Harry crawls through the mud with ease as James Corden panics about following him
Corden said: 'I know we're both a long, long way away from home. Your life now is particularly different to your life back home and particularly when you were in the military.
'So I've actually arranged a little something to take you back to your roots. A little taste of military life, as a gift from me to you, and I'm already regretting saying I'll be part of it.'
Sam noted that Harry had military experience, before Corden joked that he was 'very much a member of the BTS Army' – a reference to fans of the K-pop boy band.
They first had to climb over two large rectangular pieces of wood, before jumping through tyres on the ground and then pulling a weight on a rope.
The duo then had to crawl through mud under wire, with Corden initially complaining that it was 'too muddy'.
The pair crawled under wire through mud, with the slower Corden needing encouragement
Harry throws a spear towards a target in one of the eight challenges in the assault course
But Harry joked: 'James, get over it, you've been in LA too long, this is like a mudbath, like a facial.'
Corden hit back, saying: I have no interest - that's disgusting. That is a joke, you're (Sam) a joke.'
They then had to throw a spear towards a target, and climb up a rope to ring a bell –the latter of which only Harry achieved, prompting Corden to joke: 'That counted for both of us.'
They also had to run with a heavy ball and climb over a frame with a board over the bottom section, meaning they had to lift themselves up.
Harry achieved this without any trouble, but Corden ran off and came back with a stepladder, admitted that it was 'terrifying' as he went over the top of the frame.
The duo went to the assault course which Corden organised to remind Harry of his Army roots
Harry lifts a heavy weight which was among the challenges in the exercise in Los Angeles
As Corden began his descent, Harry jokingly encouraged him, saying: 'You look great from down here. You're doing great, well done.'
But Corden said: 'I feel like I'm Archie at a playgroup the way you're talking to me.' He had earlier joked that Harry was talking to him like he was a 'dog'.
They raced on flat ground to the end - and Harry initially let Corden run past him, but he then sprinted past him to win the challenge.
After finishing the course, Harry exclaimed: 'That was quite fun - i enjoyed that. Same time tomorrow?
Last week it emerged Harry will be forbidden by tradition from wearing full military regalia after suffering the bitter blow of losing his honorary Forces appointments.
Prince Harry climbs a rope to ring a bell, something Corden was unable to follow him in doing
Harry initially let Corden run past him but he then sprinted past him to win the challenge
With the duke no longer returning as a working member of the Royal Family, his honorary roles, such as Captain General of the Royal Marines, will be returned to Her Majesty before being redistributed among other senior royals.
Harry will be prevented – if only by tradition – from wearing full military regalia. Should he attend a Remembrance Sunday event he could wear his medals and a regimental beret but not a uniform.
Garments he should no longer wear are understood to include the Blues and Royals frockcoat worn on his wedding day in May 2018 and the Royal Marines dress uniform he wore to the Royal Albert Hall in March 2020, shortly before he stepped down as a senior royal.
Back in 2005 Prince Harry, then aged only 20, climbed the ornate steps of the Old College at the Royal Military Academy Sandhurst (RMAS) to begin his officer training.
Prince Harry (right) races to scramble his Apache at Camp Bastion in Afghanistan in 2012
Prince Harry in fatigues uniform practising for the military tattoo at Eton College in May 2005
It was widely remarked in the following years that the Army became his family.
The three honorary military titles that Prince Harry has lost
Captain General, Royal Marines
As the ceremonial head of the Royal Marines, Harry was appointed in December 2017, succeeding the Duke of Edinburgh. He made numerous visits to the Commando Training Centre in Devon and to Norway for arctic warfare drills. He made his last appearance in Royal Marines uniform at a concert at the Royal Albert Hall in March 2020.
Honorary Air Commandant of RAF Honington
Appointed by the Queen in 2008 and visited the base on at least three occasions in his formal role. In 2010 he presented the families of two servicemen killed in Afghanistan with the Elizabeth Cross. Royal Air Force Honington, near Bury St Edmunds, is the RAF’s centre of Force Protection.
Commodore-in-Chief, Royal Navy Small Ships and Diving
Appointed in August 2006 in recognition of the links between the Navy and the Royals. Opened the £30million Amphibious Centre of Excellence at Devonport Naval Base in 2013.
He subsequently served his country with distinction on the frontline in Afghanistan, both as a soldier on the ground and later as a helicopter pilot.
After Sandhurst Prince Harry commissioned as a Second Lieutenant in the Blues and Royals, a regiment of the Household Cavalry, in 2006. A debate soon began about whether he could deploy with his unit to Iraq.
As he was not directly in line to the throne many senior army figures thought he should go.
Eventually the Ministry of Defence, after drawn-out discussions with Buckingham Palace, was persuaded that he would be a high profile target whose presence would endanger those deployed with him.
His commander General Lord Dannat then personally arranged for Prince Harry to serve in Afghanistan.
He struck a deal with media outlets for them not to report his presence in return for interviews to be published and broadcast on his return.
The deal held for ten weeks, allowing Harry to experience the brutal realities of warfare.
He served as a Forward Air Controller with a desert reconnaissance unit.
In doing so he became the first member of the Royal Family to serve on the frontline since Prince Andrew took part in the Falklands War in 1982 as a helicopter pilot.
On his return to the UK from Afghanistan Prince Harry was advised to retrain as a helicopter pilot should he wish to go back to the conflict – though secretly few senior officers expected him to pass the necessary selection tests.
But he defied their low expectations, qualifying as an Apache helicopter co-pilot and gunner.
He returned to Helmand Province in September 2012 with the Army Air Corps and duly completed a four-month operational tour.
Harry, 36, will be prevented from wearing full military regalia and stripped of royal patronages
Garments Harry should no longer wear are said to include the Blues and Royals frockcoat worn on his wedding day in May 2018 (left) and the Royal Marines dress uniform he wore to the Royal Albert Hall in March 2020 (right), shortly before he stepped down as a senior royal
Harry then focused on veterans' welfare and helped set up the Invictus Games, a version of the Paralympics for injured military personnel, before retiring from the Army in June 2015.
In December 2017, Harry accepted the role of Captain General of the Royal Marines from his grandfather, the Duke of Edinburgh, who had served in this capacity for a remarkable 64 years.
The prince made a number of visits to the Commando Training Centre Royal Marines (CTCRM) in Lympstone, Devon, and to Norway where Marines practise arctic warfare.
It has been speculated that the Captain General's role could pass to Prince William or the Princess Royal.
Harry will also relinquish his roles as honorary commandant of RAF Honington and Commodore-in-Chief of the Royal Navy's Small Ships and Diving.