By LUKE SALKELD
Last updated at 4:38 PM on 18th March 2010
His three-year-old son was fighting for his life and in desperate need of a kidney.
And after fighting for his country, the 29-year-old did not hesitate in attending to his familial duties when he landed in the UK, and promptly donated an organ.
Kicking a football with his son a few months later, it looks like a case of mission accomplished.
To the rescue: James King plays football properly for the first time today with his four-year-old son James Junior, after donating one of his kidneys last December
The Daily Mail revealed in December how Marine King came to the rescue of his son, also called James, who has suffered from chronic kidney disease since birth and was struck down with a life threatening infection.
'Little James', as he is known, who is now four, was put on the organ transplant list at the age of two, and his father was found to be a match.
But the couple were told they would have to wait until their only child was at least seven before he was big enough to accept an adult organ, especially from his father, who is 6ft 4in.
Speedy recovery: James' body accepted his father's kidney and now he's expected to start school in September
While Marine King was in combat in the Middle East, however, his son's condition deteriorated and doctors decided to take the risk.
Just four weeks after he came back, he underwent the operation last November which has changed his son's life.
And today the boy's mother Louise, 33, said the operation has given him a new lease of life. She said: 'It has all gone really well.
'There are a few underlying issues, but physically James is a lot stronger and like any other child, he doesn't stop running and has got more energy.'
She continued: 'Before, he got tired and would not have managed a whole hour of exercise.
'He definitely needed the kidney transplant and the earlier he got it, the better.
'It was not nice for him being on dialysis and now this will take him through the most important years of his life.'
James was diagnosed with kidney complications during a routine pregnancy scan, when a blocked tube was hampering his development in the womb.
A blood test five days after his birth revealed damaged kidneys and he has undergone peritoneal dialysis from the age of 18 months.
His only hope of long-term survival was a kidney transplant.
Doctors had hoped to delay the transplant until James was older to increase the chances of it being a success.
But he was struck down with peritonitis last June, which meant he had to travel to hospital three times a week for dialysis on a machine used for adults.
The following month a date was set for the operation while his father was on his second tour of Afghanistan with 3 Commando Brigade.
Life saving: James King junior awaits a kidney transplant operation last December
On their wedding day: James and Lorraine King were first told that they would have to wait until their son was seven until he could accept an adult organ
He flew back when his tour ended last November and underwent the operation at Southmead Hospital in Bristol. Marine King, who is currently based in Plymouth, spent three weeks recovering from the three hour operation in hospital.
After the operation, Marine King said at the family home in Yeovil, Somerset: 'Louise and a lot of our relatives had tests to see if they were a match, but I really wanted it to be me so that I could do this for him.
'Luckily so far it has worked, and it's a miracle how much he's changed.'
Now that James' body has accepted the new organ, he is expected to start school in September.