Prince Harry paid heartfelt tribute to VJ Day heroes, including his late grandfather, Prince Philip, in a very discreet way during Friday’s poignant service, The Post can confirm.

While the Duke of Sussex remained in Montecito, Calif., during the Aug. 15 Victory over Japan commemorations, Harry did enlist the help of his close friend to place a letter and a wreath on his behalf.

Harry’s pal, whose name has not been revealed, discreetly placed the items at the Burma Star Memorial at the National Memorial Arboretum in Staffordshire, England.

However, the duke specifically asked that it be laid only after King Charles and Queen Camilla had exited the remembrance service, which marked 80 years since Japan’s surrender at the end of the Second World War.

Harry, who has 10 years of military experience under his belt, mentioned his late grandfather in the letter, which was addressed to the “Forgotten Army.”

The “Spare” author, 40, stated that their “courage and endurance” were “anything but forgettable,” per GB News.

“For me, this anniversary carries an added layer of meaning,” the duke wrote. “My late grandfather, Prince Philip, Duke of Edinburgh, served in the Pacific campaign.”

“He spoke with quiet humility about those years, but I know how deeply he respected all who stood beside him in that theatre of war,” the Invictus Games founder went on.

“Today, as I think of him, I think also of each of you, of the shared hardships, the bonds forged, and the legacy you leave.”

The royal, who rose to the rank of captain during his time in the military, said he’s “humbled” by the example of the VJ Day heroes, saying he is “proud” and “grateful” for their service and dedication.

“Your story is part of our shared heritage, and it must never be forgotten. With the deepest respect, thank you,” added Harry, who had completed two tours of Afghanistan, where he flew in combat missions.

The duke’s grandfather, who died in 2021 at age 99, was famously onboard the destroyer HMS Whelp in Tokyo Bay when Japanese officials signed the surrender on the USS Missouri.

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His son, King Charles, spoke publicly of his father’s past during the 75th anniversary back in 2020 — though he made no mention of the late duke in his address to the nation Friday.

Instead, His Majesty paid tribute to his great-uncle, Earl Mountbatten, who, as supreme Allied commander of the South East Asia Command, played a key role in halting the Japanese advance toward India.

Harry, for his part, continued in his letter, “You faced an enemy determined to the last, fought in unforgiving terrain, and endured months, even years, far from home, in conditions most could scarcely imagine.

“Your service in the jungles and mountains of Burma and beyond was marked by grit, unity, and sacrifice.”

“It is because of that sacrifice that generations since, myself included, have been able to live in freedom,” he went on.

“From the lessons of that bitter struggle came the understanding that even the fiercest of foes can, in time, become valued partners in peace.”

The poignant letter was signed “Prince Harry, Duke of Sussex” and featured the duke’s cypher of an H underneath a crown.

In 2020 — the year Harry and his wife, Meghan Markle, quit royal life and moved to the US — the duke was left disappointed after his request to lay a wreath at the Cenotaph was denied.

Months later, the late Queen Elizabeth II stripped Harry of his military patronages following his decision to step down as a senior member of the Firm.