The Duke of Cambridge felt his late mother Princess Diana walking "beside" him at her funeral procession.
The 35-year-old lost his parent in 1997 when he was only 15 years old, and Prince William has admitted when he and his younger brother Prince Harry held the coffin he could feel his mother's presence helping him get through.
Speaking in a BBC One documentary titled 'Diana, 7 Days', William said: "It was one of the hardest things I've ever done.
"I felt like she was almost walking along beside us, to get us through it."
And William - who has four-year-old son Prince George and two-year-old daughter Princess Charlotte with his wife the Duchess of Catherine - has revealed he can remember the sadness that hit every guest at Diana's funeral, which he noticed when he shook people's wet hands from where they wiped away their tears.
He explained: "I remember people's hands were wet because of the tears that they'd just wiped away."
The programme will air on August 27 to mark the 20th anniversary since Diana passed away, which William and Harry decided to go ahead with because they felt they had let their mother down.
Speaking previously, William said: "Part of the reason why Harry and I want to do this is because we feel we owe it to her. I think an element of it is feeling like we let her down when we were younger.
"We couldn't protect her. We feel we at least owe her 20 years on to stand up for her name and remind everybody of the character and person that she was. Do our duties as sons in protecting her."