He was the only 1916 leader to be executed outside Ireland
Roger Casement is being remembered on the centenary of his execution.
He is considered one of the most important figures involved in the fight for Irish independence.
Casement had become a member of the Gaelic League in 1904, and wrote nationalist articles under the pseudonym 'Seán Bhean Bhocht'.
He retired from the British consular service in 1913, after which he joined the Irish Volunteers.
He was dispatched to Germany to raise an Irish Brigade from Irish prisoners of war.
He was captured in Kerry in 1916 on Good Friday, having returned to Ireland in a German U-Boat.
Casement was imprisoned in Pentonville Gaol in London, where he was tried on charges of high treason.
He was hanged on August 3rd 1916, the only leader of the Rising to be executed outside of Ireland.
In 1965 his body was returned to Ireland, and he was laid to rest at Glasnevin Cemetery.
Irish Aid and the Defence Forces have commemorated his contribution to international human rights, by hosting a free open day for families and the general public from at Casement Aerodrome in Baldonnel.
The Aerodrome is usually closed to the public, but has been transformed with market stalls, picnic areas, play areas and other activities.
Military vehicles, vintage aircraft and rare memorabilia are also on display, as well as special military capability displays by members of the Air Corps and Defence Forces.
Meanwhile, a programme of exhibitions and talks on Casement, his life and legacy is taking place throughout the day.
Guest speakers are participating in a panel discussion to explore some of the issues and challenges facing those working in the field of human rights today.
Several agencies and organisations have information stands at the event, including: Irish Aid, Tearfund Ireland, Kimmage Development Studies, Habitat for Humanity Ireland, Irish Red Cross, World Vision Ireland, UNICEF Ireland, Trócaire, Gorta Self-Help Africa, Plan International and Oxfam Ireland.
Tributes have also been paid at Glasnevin Cemetery, where a memorial has been unveiled.
Minister of State for the Diaspora and Overseas Development Aid, Joe McHugh, said: "Casement's desire to address inequality in the world has been shared by generations of Irish people."
"The Government’s Irish Aid programme has its roots in Ireland's missionary tradition and for many decades Irish Aid has provided help to the most vulnerable in the world. Ireland also has a strong record in UN peacekeeping, and we are known for promoting human rights."
"As we remember Casement's legacy today, I want to also pay tribute to members of the Irish diaspora who are making real contributions to overseas development and to members of the Defence Forces currently serving overseas on UN peacekeeping missions."