Prince William had a falling out with Prince Harry over his relationship with Duchess Meghan in 2018.

That much was always thought to be true, but a new excerpt from author Robert Lacey's Battle of Brothers has revealed, in heartbreaking detail, the very moment that fractured the bond between brothers.

Moment that broke William and Harry apart revealed

The downfall of William and Harry's relationship did have to do with Meghan, but it wasn't just because William thought his brother was going too fast early in his relationship with the Suits actress.

Rather, the brothers had a blow-up argument over the bullying accusations made against Meghan by Kensington Palace staff, according to a new excerpt of Lacey's book released in The Times this weekend.

Pinterest
The Real Moment That Divided William And Harry Revealed

The bullying allegations only went public in 2021, days before the Oprah interview. But back in 2018, Prince William had grown suspicious of Meghan and told friends he thought she had an "agenda" and was "stealing" his brother, Lacey claims.

After William learned that Meghan was allegedly bullying Palace staff, he and his brother had a heated phone call. Harry "flared up in furious defense of his wife," Lacey writes, and "shut off his phone angrily."

Prince William then confronted Harry in person and they had a "showdown" that was "fierce and bitter," according to Battle of Brothers.

This argument broke off communication between the brothers, and it occurred before Harry and Meghan toured Australia in October 2018 — when relations were thought to have gone south between Harry, Meghan and the royals.

"April Curtis" looks as stunning as ever...!

'Knight Rider': What Does Rebecca Holden Look Like Today?

New Prince Harry, Prince William claims ahead of UK reunion

Lacey's new update to Battle of Brothers adds to comments Prince Harry made in the Oprah interview, where he suggested the Royal Family disliked how Meghan easily thrived in royal work and received a glowing reception on the Australia tour.

Pinterest
Prince Harry and Duchess Meghan on their Australia tour in 2018.

But it was the bullying allegations and the resulting feud that split William and Harry, according to Lacey. William also divided their households after that time.

The claims also come just days before Prince Harry will reunite with his brother in the UK to honour what would've been Princess Diana's 60th birthday on July 1.

As for the bullying accusations against Meghan, there hasn't been an update on the Palace's investigation since the claims were made in early March.

At the time, the Duchess said she was "saddened" by the allegations but dismissed them as an "attack on her character."

'Falcon Crest': "Chase Gioberti" and "Maggie Gioberti".

Robert Foxworth left the show in 1987!

'Falcon Crest': "Chase Gioberti" Today