AceShowbiz - King Charles III included his son Prince Harry in a post celebrating Father's Day. On Sunday, June 18, the British monarch took to Instagram to share a sweet throwback photo of himself with his sons, Prince William and Prince Harry.

The picture featured young Harry pointing at something while the three of them standing on the rocks. William and Charles could be seen looking in the direction with curious faces.

The snap was reportedly taken on August 16, 1997, just two weeks before the boys' mom, Princess Diana, died. The young royals were on holiday with their father at Balmoral Castle in Scotland at the time. They were due to meet the late royal on August 31, the day she was killed in a car crash.

Charles also included images of Charles with his own father, the late Prince Philip, and Queen Camilla with her late dad, Bruce Shand. "To Dads everywhere, we wish you a special Father's Day today," the caption read.

The post came amid Harry and his father Charles' rocky relationship in the last few years. In Harry's explosive memoir, "Spare", the Duke of Sussex accused his father of being emotionally distant with him at times. He also talked about Charles' "sadistic" jokes that he wasn't Harry's "real" father.

"Pa liked telling stories, and this was one of the best in his repertoire. He'd always end with a burst of philosophizing … Who knows if I'm really the Prince of Wales? Who knows if I'm even your real father?" Harry wrote in his book.

Seemingly in response to the damning memoir, Charles evicted Harry and his wife Meghan Markle from their English abode, Frogmore Cottage just days after the book was released.

Despite the family feud, Harry flew to London to attend his father's coronation back on May 6. The Duke, however, returned to the U.S. as soon as the ceremony ended because he didn't want to miss his son Prince Archie's birthday, which also happened to fall on May 6.