reported that the beard was an attempt to disguise his identity during the mission.
He was also following family tradition, as his father Prince Charles had grown a beard while on Naval exercises in Alaska in 1975.
Some fans have even compared William to his great-great grandfather, King George V.
It seems he liked the scruffy look, as he was still working it when he attended the royals' annual Christmas Day service at Sandringham a few weeks later.
In a twist of events, Harry was fluff-free at the time.
Unfortunately for Wills, now 39, he had to shave his facial hair off before joining the Air Force, as it doesn't permit facial hair.
But now that his time with the RAF has come to an end, royal fans are hoping that the fuzz may make a comeback.
Tweets have emerged saying: "Prince William NEEDS to grow a beard," and: "I'm gonna need Prince William to shave his head and grow a beard."
It's been over 10 years since we last saw the beard, so we reckon it could be the perfect time for Wills to give it another whirl.
We wonder if Kate Middleton would approve?