The couple took part in ceremonies at Dublin's Glasnevin Cemetery.
They paid tribute to Victoria Cross recipients and to the almost 500 people who died in the failed 1916 rebellion against Britain rule.
The couple's four-day visit to the Republic of Ireland and Northern Ireland will end later on Friday.
It will culminate with an event hosted by the British ambassador in Dublin.
The royal couple spoke with Irish politicians on Friday, including Taoiseach (Prime Minister) Enda Kenny and Sinn Féin leader Gerry Adams.
Mr Adams said the prince had commiserated with him over the death of Martin McGuinness, the IRA paramilitary-turned-peacemaker who died in March.
The pair "enjoyed some banter" about which of them was the oldest, added Mr Adams.
On Friday, the prince and the Republic of Ireland's Arts and Heritage Minister Heather Humphreys laid wreaths at the Cross of Sacrifice in Glasnevin Cemetery that honours those killed during the two world wars.
The prince also took part in a ceremony unveiling stones remembering the four Irish soldiers who were awarded Victoria Crosses 100 years ago.
He toured the republican plot in the cemetery and visited the graves of Michael Collins and Éamon de Valera.
After that, he unveiled another wreath at a wall in Glasnevin that remembers all those who died during the Easter Rising in 1916.
On Thursday, Prince Charles tried his hand at hurling at Kilkenny Castle.
He and the Duchess of Cornwall also enjoyed a demonstration of the ancient Irish sport.
Their visit to the Republic of Ireland, which followed a stay in Northern Ireland, was at the request of the British government.
They also visited the Curragh Military Camp, where Irish UN peace-keeping soldiers are trained.
On Thursday morning, the Royals visited a farmers' market in Kilkenny, and they met some of the thousands of people who had lined the streets there.
The couple left Northern Ireland on Wednesday, after Prince Charles opened a garden of remembrance for police officers killed on duty in Northern Ireland.
They also visited the Seamus Heaney Homeplace Centre in Bellaghy, where they met members of the poet's family.
The Prince of Wales and the Duchess of Cornwall have honoured Irishmen who fought for Britain and all the people who died in the 1916 Easter Rising.