Dr. Tessy Ojo, CEO of The Diana Award, tells PEOPLE that Prince William and Prince Harry mirror their mother, Princess Diana, and her ability to go “where the pain was.”

"My mother would have been horrified that anyone’s children or grandchildren would live in a world still infested with mines.”

He told Harry: "Prince Harry, thank you for your leadership, for your heart, for your vision, for sustaining the legacy of your mother and for inspiring a whole new generation around the world to be engaged in this critical work against the scourge of land mines.”