The Duke and Duchess of Sussex attended an informal meeting of the U.N. General Assembly in New York on Monday to mark the observance of Nelson Mandela International Day.

The international celebration honors the life of South African anti-apartheid activist Nelson Mandela, who also served as the country's first democratically elected president, and is held annually on his birthday, July 18.

Prince Harry spoke before the assembly on Monday, reflecting on Mandela's legacy and how the world might carry it forward.

"We can find meaning and purpose in the struggle," he said, remarking on the issues facing people across the globe, including COVID-19 and various civil and human rights battles. "We can wear our principles as armor. Heed the advice Mandela once gave his son, to 'never give up the battle even in the darkest hour,' and find hope where we have the courage to seek it."

PHOTO: Meghan, Duchess of Sussex and Britain's Prince Harry arrive to celebrate Nelson Mandela International Day at the United Nations Headquarters in New York, July 18, 2022.
Brendan Mcdermid/Reuters
Meghan, Duchess of Sussex and Britain's Prince Harry arrive to celebrate Nelson Mandela International Day at the United Nations Headquarters in New York, July 18, 2022.
PHOTO: Britain's Prince Harry and his wife Meghan, Duchess of Sussex arrive to celebrate Nelson Mandela International Day at the United Nations Headquarters in New York,  July 18, 2022.
Shannon Stapleton/Reuters
Britain's Prince Harry and his wife Meghan, Duchess of Sussex arrive to celebrate Nelson Mandela International Day at the United Nations Headquarters in New York, July 18, 2022.

He also mentioned the time the late human rights icon and South African Archbishop Desmond Tutu gifted him an image of his mother Princess Diana with Mandela from 1997.

Read his full speech below:

Thank you to the president of the General Assembly, His Excellency Mr. Abdulla Shahid, for the introduction.

And thank you to the Nelson Mandela Foundation for inviting me to speak on this day of all days. And thank you to Secretary-General Guterres and the United Nations -- whose promise reflects Mandela's vision of a freer, more peaceful world -- for hosting us today.

It is an honor to join you all on Nelson Mandela International Day. Having spent time with many of Mandela's family members over the years, I speak to you today with humility, mindful of how much the man they loved means to so many.

Those of us not fortunate enough to know Mandela well have come to understand the man through his legacy -- the letters he wrote alone in his prison cell, the speeches he delivered to his people and those incredible shirts he sported.

We've also come to know him through the photographs of a person who, even when confronting unimaginable cruelty and injustice, almost always had a smile on his face. For me, there's one photo in particular that stands out.

PHOTO: Britain's Prince Harry, Duke of Sussex addresses the United Nation General Assembly for the 2020 UN Nelson Mandela Prize at the United Nations (UN) headquarters in N.Y., July 18, 2022.
Jason Szenes/EPA via Shutterstock
Britain's Prince Harry, Duke of Sussex addresses the United Nation General Assembly for the 2020 UN Nelson Mandela Prize at the United Nations (UN) headquarters in N.Y., July 18, 2022.

On my wall, and in my heart every day, is an image of my mother and Mandela meeting in Cape Town in 1997.

The photo was presented to me by the late Archbishop Desmond Tutu, whose friendship and inspiration were their own treasured gift. My wife and I had the honor of introducing our 4-month-old son to him back in 2019.

When I first looked at the photo, straight away what jumped out was the joy on my mother's face. The playfulness, cheekiness, even. The pure delight to be in communion with another soul so committed to serving humanity.

And then I looked at Mandela. Here was a man with the weight of the world on his shoulders, asked to heal his country from the wreckage of its past and transform it for the future.

A man who had endured the very worst of humanity, vicious racism and state-sponsored brutality. A man who had lost 27 years with his children and family that he would never get back.

Twenty-seven years.

Yet, in that photo and so many others, he is still beaming. Still able to see the goodness in humanity. Still buoyant with a beautiful spirit that lifted everyone around him.

Not because he was blind to the ugliness, the injustices, of the world -- no, he saw them clearly; he had lived them -- but because he knew we could overcome them.

In our own time, a time of global uncertainty and division, when it's all too easy to look around and feel anger or despair, I've been inspired to go back to Mandela's writings for insight into how this could be -- how he could experience so much darkness and always manage to find the light. There I found a few lines that stopped me in my tracks.

In a letter from prison, he wrote:

"I feel my heart pumping hope steadily to every part of my body, warming my blood and pepping up my spirits. I am convinced that floods of personal disaster can never drown a determined revolutionary… To a freedom fighter, hope is what a life belt is to a swimmer -- a guarantee that one will keep afloat and free from danger."

It moved me even more when I saw the date: August 1, 1970. Seven years into Mandela's imprisonment, not even one-third of the way through.

In those circumstances, how many of us would have lost hope, and let our life belts slip away? How many of us would have been broken by a system designed to do exactly that?

And let's be honest: How many of us are in danger of losing those life belts right now? How many of us feel battered, helpless, in the face of the seemingly endless stream of disasters and devastation?

I understand. This has been a painful year in a painful decade. We're living through a pandemic that continues to ravage communities in every corner of the globe.

Climate change wreaking havoc on our planet, with the most vulnerable suffering most of all. The few weaponizing lies and disinformation at the expense of the many. And from the horrific war in Ukraine to the rolling back of constitutional rights here in the United States, we are witnessing a global assault on democracy and freedom -- the cause of Mandela's life.

According to Freedom House, our world has grown less free every year, for more than a decade and a half.

As so often happens in history, the consequences of decisions made by some of the most powerful people in some of the wealthiest countries are being felt even more deeply across the continent of Africa.

The pandemic, the war and inflation have left Africa mired in a fuel and food crisis, the likes of which we have not seen in decades. Worse still, this comes at a time when the Horn of Africa is enduring the longest drought it's faced in close to half a century. And what is happening in Africa is not an isolated event. The drought there is a reflection of extreme weather we are seeing across the globe. As we sit here today, our world is on fire, again.

And these historic weather events are no longer historic. More and more, they are a part of our daily lives and this crisis will only grow worse… unless our leaders lead. Unless the countries represented by the seats in this hallowed hall make the decisions -- the daring, transformative decisions -- that our world needs to save humanity.

These decisions may not fit the agendas of every political party. They may invite resistance from powerful interests. But the right thing to do is not up for debate. And neither is the science. The only question is whether we will be brave enough and wise enough to do what is necessary.

So yes, this is a pivotal moment -- a moment where multiple converging crises have given way to an endless string of injustices -- a moment where ordinary people around the world are experiencing extraordinary pain.

And in this moment, we have a choice to make.

We can grow apathetic, succumb to anger or yield to despair, surrendering to the gravity of what we're up against.

Or we can do what Mandela did, every single day inside that 7-by-9-foot prison cell on Robben Island -- and every day outside of it, too.

We can find meaning and purpose in the struggle. We can wear our principles as armor. Heed the advice Mandela once gave his son, to "never give up the battle even in the darkest hour." And find hope where we have the courage to seek it.

Since I first visited Africa at 13 years old, I've always found hope on the continent. In fact, for most of my life, it has been my lifeline, a place where I have found peace and healing time and time again.

It's where I've felt closest to my mother and sought solace after she died, and where I knew I had found a soulmate in my wife.

And it's why so much of my work is based there. Because, despite continued hardship, there are people across Africa who embody Mandela's spirit and ideals -- building on the progress he helped make possible.

I see it in the communities fighting to save the Okavango Delta, defying the odds to protect their home and its biodiversity from big oil companies.

I see it in the young girls who were forced out of school and into marriage in Northern Nigeria, speaking out today so others may get a fuller chance to thrive tomorrow.

I see it in the young entrepreneurs I met in Johannesburg, using their energy and creativity to launch businesses that serve their communities.

I see it in World Central Kitchen, a partner of the Archewell Foundation, and their volunteers in Ukraine and around the world, fighting food insecurity one meal at a time.

I see it in the vulnerable children of Lesotho and Botswana orphaned by HIV, striving for a brighter future, which we support through our organization, Sentebale.

I see it in the newest generation of activists for equality and justice, who are mobilizing people of all ages and races, all faiths and walks of life, to lace up their shoes and join the march.

And I see it in the parents I meet around the world, as determined as Mandela was, to give their children a better shot at a brighter future, to prioritize their own and their children's mental health and wellbeing, to reject old ideas and past prejudices… to heal from the past and build resilience for the present and future, because they know the price of inaction will be paid by the next generation.

In their strength and in their deeds, Mandela's legacy shines as brightly as ever. They are my life belt. I hope they can be yours, too.

Because right now, the water is rising all around us -- in some places, quite literally.

So it's more important than ever that we seek a purpose greater than ourselves, and get to work.

After all, Mandela was not only a man of conscience. He was a man of action. He organized millions. Inspired billions. Joined hands -- not only with those who loved him, but those who had once jailed him -- to build a better future for all.

What Mandela understood was that true legacy transcends one's own needs and the passage of time. It defies the moment -- its relevance never ceases. Legacy does not belong to the self. It belongs to those it impacts.

That doesn't mean he was perfect. No, he was something better. He was human. As he wrote in his autobiography:

"I have made missteps along the way. But I have discovered the secret that after climbing a great hill, one only finds that there are many more hills to climb. I have taken a moment here to rest, to steal a view of the glorious vista that surrounds me, to look back on the distance I have come. But I can rest only for a moment, for with freedom comes responsibilities, and I dare not linger, for my long walk is not yet ended."

It has been almost a decade now since Mandela's own walk on this Earth finally reached its end. But what he taught us again and again is that it was never his walk alone.

It was all of ours. It is all of ours.

What a beautiful gift, especially as a dad of two young children myself -- the message that this world is meant to be shared, that the work of each generation is tied to those who came before and those who will come after us.

That we have an obligation to give as much, if not more, than we take and never shudder in the face of darkness, for hope is the fuel that courage requires.

So on this Nelson Mandela International Day, as a new generation comes of age, a generation that did not witness Mandela's leadership for themselves, let's commit to remembering and celebrating his life and legacy every day, not just once a year.

Let's talk with our children about what he stood for. Let's seek out what we have in common, empower all people to reclaim our democracies, and harness the light of Mandela's memory to illuminate the way forward.

Because if we can summon our own courage, just as he did, if we can see one another's humanity, just as he did, a better day will truly be on the horizon.

Thank you.

Harry's address comes 25 years after his mother Diana met Mandela during the trip to South Africa he mentioned in his speech.

The two met in March 1997 at Mandela's Cape Town home and discussed the issue of AIDS in the country. Diana dedicated much of her own time in the 1990s working on the issue, helping to destigmatize the disease and change misconceptions on how HIV/AIDS is transmitted.

PHOTO: In this March 17, 1997 file photo, South African President Nelson Mandela, left, shows the way to Princess Diana, during a meeting in Cape Town, South Africa.
Sasa Kralj/AP, FILE
In this March 17, 1997 file photo, South African President Nelson Mandela, left, shows the way to Princess Diana, during a meeting in Cape Town, South Africa.

Harry has since continued his mother's legacy on the topic, becoming one of the leading worldwide advocates in the fight against AIDS and HIV. In 2018, he joined forces with Elton John at the International AIDS Conference in Amsterdam to shine a spotlight on the disease.