Patrick Denis O'Donnell (9 January 1922 – 1 January 2005) was an Irish military historian, writer, former UN peace-keeper, and Commandant of the Irish Defence Forces. Background He was born in the Kerries Tralee, County Kerry, only child of Denis O'Donnell, and Hannah Leane, and was also known as "Paddy" or "P.D.". He was a direct descendant of John O'Donnell of Ardfert, and descended from an O'Donnell of Tyrconnell, following on the implantation of O'Donnells in Ardfert by Prince Hugh Roe O'Donnell en route to the Battle of Kinsale in 1601, as recorded in the Annals of the Kingdom of Ireland. He married Stephanie Sarah Teresa Tyndall in 1952, daughter of David P. Tyndall and Sarah née Gaynor, and they lived in Fingal, north Dublin. They had three children, Frank (see Francis Martin O'Donnell), Sally, and Nola. He was a cousin of Maurice Gerard Moynihan, with shared interests in historical matters. Education He was educated in Tralee Christian Brothers Schools and joined the Irish Army in 1940. He successfully completed management and psychology courses at the School of Management at Rathmines Technical School. He graduated from the Irish Military College in the Curragh, and was commissioned in 1943. He also graduated from the Infantry School on 13 April 1949, with distinction. Later he attended the Public Relations Institute of Ireland in the early 1960s, and conducted public relations campaigns for the visit of US President John F. Kennedy to Ireland in 1962 Military career He served during the "Emergency" as the period of the Second World War was known in then-neutral Ireland. He served briefly, with commendation, as a United Nations Military Observer with the United Nations Truce Supervision Organisation for Palestine (UNTSO), during the years 1965–1967, successively in Jerusalem, Tiberias, and Damascus. Later, he held senior responsibilities in the Observer Corps (the Irish Army's unit for mitigation and preparedness in the event of nuclear war), military intelligence, and border security. An amateur artist in his spare time, he designed the insignia of the 5th Infantry Battalion. He rose to the rank of Commandant (Major) before retirement. He was awarded the United Nations Medal by the United Nations Secretary-General on 30 November 1965, and the United Nations Peacekeepers Medal by the Irish Government in 1991, in recognition of his service in the cause of world peace. Historical interests He was keenly interested in Irish and Middle Eastern history and was