When Prince William stood in Westminster Abbey waiting for his bride, Kate Middleton, his brother Harry was by his side as his best man.
Long before the tensions of recent months, the two men were extremely close and Harry was thrilled to welcome Kate into the family as his sister-in-law.
Once the formalities were over, the newlyweds and their guests headed off to a private reception and it was time for Harry's most important best man task - the speech.
His words reportedly went down a storm, with guests laughing and crying throughout.
As well as making lots of jokes at his brother's expense he told sweet stories and said their love inspired them, which brought a tear to Kate's eye.
And there was one very cheeky joke he had planned but his then-girlfriend Chelsy Davy stepped in and made him cut it out as she thought it was too much.
According to royal expert Katie Nicholl, Prince Harry wanted to talk about his new sister-in-law's "killer legs" - risky for any bride, let alone the future Queen consort...
In her book Harry: Life, Loss and Love, Katie explains that Harry asked Chelsy to read over his speech and check it before the big day.
She writes: "She had helped Harry edit the best man's speech, sensitively advising him to take out a line about Kate’s 'killer legs' that might have embarrassed the bride."
Harry met Chelsy at school and they dated on and off between 2004 and 2011.
The prince reportedly asked her to be his plus one at Kate and William's wedding in a bid to rekindle their relationship but it actually had the opposite effect.
Chelsy had been unsure about royal life and the huge and lavish ceremony is what apparently confirmed her fears that royal life wasn't for her.
Writing in royal biography Harry: Conversations with the Prince, journalist Angela Levin said: "A friend revealed that seeing the enormity and pomp of the day convinced Chelsy that she and Harry had been right to separate.
could never have worked, especially as she valued her privacy and guarded it so carefully."
The pair are believed to still be good friends and Chelsy was a guest at Harry's wedding to Meghan Markle last year.
This gave her the chance to watch on first hand when William got revenge on his brother with his own best man speech when he returned the favour and acted as his best man.
This gave her the chance to watch on when Wills got his own back when he returned the favour and gave a best man's speech at the Sussexes' wedding.
One of the guests told the Sunday Times the second in line to the throne made a "filthy" joke about wet knickers in his best man speech.
Unfortunately details of the joke haven't been leaked - but we really hope we find out at some point!
William also pulled a prank on his little brother at the party, and nearly "floored" some of the guests in the process.
Apparently Harry recently fell off a ladder while trying to change a lightbulb, so Wills tied a ladder to the back of the newlyweds' car.
Harry's pal Charlie van Straubenzee also spoke at the Frogmore House reception, mocking the prince for his ginger hair.
According to the Times, he questioned Harry's behaviour when he was acting as dorm monitor at Ludgrove School in Berkshire, where they were both students.
He said: "All I wanted was a cuddle from my mummy.
"Instead Harry nicked my teddy bear and chucked it out on to the roof. Ladies and gentlemen, I ask you, how can you put someone in charge of a dorm when that someone is worse behaved than the whole dorm combined?"