Prince Harry has said that he and Meghan Markle felt they had 'no other option' but to stand down from their royal duties.
The Duke of Sussex said he and Meghan had hoped to continue serving the Queen, the Commonwealth and his military associations, without any public funding, but this was not possible.
In his first public speech since the couple's decision to step down as senior royals, Harry said he wanted his family to have a "more peaceful" life.
He added: "Once Meghan and I were married, we were excited, we were hopeful, and we were here to serve.
"For those reasons, it brings me great sadness that it has come to this.
"The decision that I have made for my wife and I to step back, is not one I made lightly.
"It was so many months of talks after so many years of challenges.
"And I know I haven't always gotten it right, but as far as this goes, there really was no other option.
"What I want to make clear is we're not walking away, and we certainly aren't walking away from you.
"Our hope was to continue serving the Queen, the commonwealth, and my military associations, but without public funding.
"Unfortunately, that wasn't possible."
The duke was speaking at a dinner for supporters of Sentebale - his Africa-based charity supporting youngsters with HIV - at the Ivy Chelsea Garden in London.
It comes after royal family talks concluded and the Sussexes announced they will stop carrying out royal duties from the spring, no longer use the title HRH and will repay the taxpayers' millions spent on their Berkshire home.
But Harry said the couple will continue to lead a life of service, and were taking a leap of faith.
He added: "It has been our privilege to serve you, and we will continue to lead a life of service.
"I will always have the utmost respect for my grandmother, my commander in chief, and I am incredibly grateful to her and the rest of my family, for the support they have shown Meghan and I over the last few months.
"I will continue to be the same man who holds his country dear and dedicates his life to supporting the causes, charities and military communities that are so important to me.
"We are taking a leap of faith - thank you for giving me the courage to take this next step."
Meghan and Harry have already begun a transition phase of living in Canada and the UK.
The duchess is in the Commonwealth country with son Archie, where the Sussexes spent six weeks over the festive period.
The move was agreed by the Queen, Prince of Wales and Duke of Cambridge following the Sussexes' unprecedented statement released earlier this month.
It is understood the couple will now spend the majority of their time in Canada, with Harry expected to join his wife sometime this week.
The Sussexes keep the style of HRH - His or Her Royal Highness - but the statement issued on their behalf said it will no longer be used from the spring "as they are no longer working members of the royal family".
Harry's mother, Diana, Princess of Wales, was stripped of her HRH in 1996 following her divorce from Charles.
The Duke will continue to work with his charities and organisations like the Rugby Football League and Sentebale - his Africa-based charity supporting youngsters with HIV - and the duchess will also keep supporting the good causes close to her heart.
Harry will give up a Commonwealth role and his three military appointments, the most prominent being Captain General Royal Marines.
All the new arrangements are due to come into effect in the spring and will be reviewed by Buckingham Palace in 12 months.
