Britain's Queen Elizabeth II was a person who modelled and witnessed reconciliation, according to the Archbishop of Armagh and Primate of All Ireland.
Eamon Martin said that she took "very courageous steps" and risks for peace.
"We all remember her visit to Ireland in 2011 and her very courageous steps in Enniskillen in 2012," he said, when she became the first of the Royal family to enter into a Catholic church.
Speaking on RTÉ's Morning Ireland, Archbishop Martin also recalled her historic meeting with Sinn Féin’s Martin McGuinness in 2014.
"Her meeting with Martin McGuinness at a very difficult time for her, and indeed for Martin McGuinness as well, to take those steps, to model that we are now in the business of building bridges rather than barriers between each other," he said.
He added that it is important that these achievements are not forgotten.
Archbishop Martin said the death of Queen Elizabeth has made people "just stop".
Her death is an historic moment that has caught an entire body of people up in the funeral, he said.
This is testament to the queen, who was clearly held in great affection and admiration across the UK, and in Ireland, he added.
Archbishop Martin said that many Catholics in Ireland saw a woman of great service and faith in Queen Elizabeth.
At the same time, she had respect for people of all and no faiths, he added.
She was clear in her respect of the Catholic faith, he said, adding that she met with five Popes and undertook a state visit to the Holy See, while Pope John Paul II also visited Buckingham Palace.
Archbishop Martin said his own encounters with Queen Elizabeth were small, but that he met her in Enniskillen in Co Fermanagh in 2012.
He said that he hoped King Charles III will continue her good work.
The archbishop said he believed today's service would be quite traditional and he understands that Queen Elizabeth had a big say in the prayers, readings and hymns.
